Veterum Testimonia Pro Eusebio: “Ancient testimonies on behalf of Eusebius"

 Ex epistola Constantini Magni ad Antiochenos … (p. 516)

“I confess I have read the Acts in which your honorable testimonies and earnest requests about Eusebius, bishop of Caesarea, are recorded—whom I too have long known well for his learning and modesty—and I have discovered that you are inclined toward him and wish to claim him for yourselves. And a little later: ‘Indeed I highly praise that man whom you judge worthy of honors and goodwill. Yet I am not so rash as to … [accept anything] that has not been reached by the proper judgment of each [church],’ etc.”

Ex eiusdem Constantini ad Eusebium epistola, qua eum laudat quod Antiochenam sedem recusaverit (p. 518)
“I have often read your letter and I recognize that you observe the yoke of church discipline with even temper. Persist, then, in that judgment which seems acceptable to God and in harmony with apostolic tradition—this is the height of prudence. We for our part hold you to be such that, by the testimony of the whole world, you might be judged worthy of a bishopric over the universal Church. But let the praise be reserved until he comes to his senses who tried to urge you, against the commands of God and the apostolic and ecclesiastical rule, to accept the Antiochene bishopric; let him rather be persuaded that the mandates of God and the rules of the Church are to be preferred in this matter.”

Ex eiusdem Constantini epistola ad synodum Antiochenam (p. 519)
“I have often read the letters of your sanctity and I have approved and praised the prudence of your colleague Eusebius. Having inquired about all that was done—partly from your letters, partly from the documents of the praetorian officials Acaeus and Strategius—I see it cannot be concealed that the pattern of your church assemblies among the people of Antioch is acceptable to God and fitting for the Church. I have therefore ordered that the most desirable example of this be appended to these letters, so that you may govern with one mind and judgment. And you should hold this firmly: since your letters agree, let the Church of Antioch, according to the suffrage of the people and the presbytery, undertake the episcopate and its care with that will and judgment which your laws of the Church at Antioch prescribe, etc.”

Ex eiusdem Constantini ad Eusebium epistola, in qua librum illius laudat (p. 543)
“I have learned of your outstanding learning and steadfast devotion to study; your work has reached me more quickly than I had hoped, and I have read it with keen pleasure. It is clear what benefit your industry brings to the churches and how much delight your writings give to all of us.”

Ex epistola eiusdem Constantini ad Eusebium de conficiendis sacrae Scripturae codicibus (p. 545)
“It has seemed good that by your God-given foresight there be prepared fifty copies of the divine Scriptures, which the holy Church of God in the city stands in pressing need of. Have them written on prepared parchment in a clear, legible hand, and arranged for use in the reading services; and take care that all necessary provision be made for this work at once, as we have instructed, so that they may be furnished for the use of the Church.”

From the book Questions on the Old and New Testament (the work commonly printed among Augustine’s writings), ch. 125.
“We recall that in a certain little book of Eusebius (as you have read in some of his other writings) he says that the Holy Spirit does not know the mystery of the Nativity of our Lord Jesus Christ; and I am astonished that a man of such learning has imputed such a stain to the Holy Spirit.”

From Jerome, Letter 65, to Pammachius and Oceanus.
“Apollinaris wrote exceedingly strong books against Porphyry; Eusebius composed the Ecclesiastical History. But the former introduced a ‘halved’ dispensation of Christ, while the latter is the most open champion of the impiety of Arius.”

From Jerome’s Apology against Rufinus.
“He—Eusebius, bishop of Caesarea—wrote six books on behalf of Origen (as I have already said), being formerly of the Arian party; it was a set and labored work. He also wrote the whole life of Origen … and, in the Catalogue—that is, according to our judgment—he is an Arian.”

Facing page (letters and notices about Eusebius; p. 69 verso)

From the same book (Jerome’s Apology):
“Eusebius himself, a lover and follower of the martyr Pamphilus, published three very elegant books which include the Life of Pamphilus. In these, while recounting the virtues of his teacher, he also carried himself to heaven in praise, as far as his doctrine and modesty would allow. And he set forth also a little treatise Against Hierocles. He placed Eusebius in the Ecclesiastical History, in the arrangement of times, among the bishops of the Holy Land; and he himself composed in Latin … [the line breaks in the image]. Now this Eusebius is not a Catholic, but an Arian.”

From Jerome, Book II Against Rufinus, Preface on Hebrew places.
“Eusebius, who had shared the favor of blessed Pamphilus the martyr, wrote ten books called the Ecclesiastical History, after his Chronological Canons, which the Latin language has translated, concerning the different nations, in which, in the mode now said, he also inserted maps, and, as it were, a topographical description of the land of Judaea and a division of the tribes, the very names of the cities; he composed in a very concise exposition pictures, and, following the order of Scripture, almost all the names of cities, mountains, rivers, and villages; and the names which remain the same and those which have been changed he indicated, with the part of the province. Whence the later [writers] who follow have admired his zeal,” etc.

From Jerome, Book II On Ecclesiastical Writers.
“Hippolytus, a most learned bishop of the Church (whose works some have claimed as their own), set forth the reason for the Paschal calculation, in Greek, as the Alexandrians are wont, and established the cycle of years which they call the enneakaidekaeteris; and Eusebius, in the book mentioned above, composed the Paschal canon from the ninth year to the circle of years, that is, the ‘period of nineteen years,’ on that occasion.”

From the same book.
“Eusebius, bishop of Caesarea in Palestine, most studious in divine writings, and with an acquaintance with books joined to zeal, composed many and notable volumes. His works are these: Gospel Questions and Answers in two books; the Evangelical Preparation in fifteen books; the Evangelical Demonstration in twenty books; On the Topography of the Hebrews in one book; a book On the Names of Places in the Sacred Scriptures, which is called the Onomasticon; Against Porphyry in many volumes, who was writing at that time; twenty books of the Chronicles; a book On the Differences of the Gospels, in which he wrote not only twenty but very many [things]; the Apology for Origen in six books; and the Life of Pamphilus the Martyr. He also wrote small works On the Martyrs. He flourished at the same time as Emperor Constantine, and [another Constantine] in Sicily; and because of the friendship of the martyr Pamphilus he also took the surname.”

From the excerpt headed “Ex libro primo excerptorum Historiae Ecclesiasticae Philostorgii” (p. 73)

Latin:
“Philostorgius Eusebium quidem Pamphili, tum ob alia multa, tum ob Historiam Ecclesiasticam laudibus afficit… Deum cognosci et comprehendi non posse existimaverit… Ceterum et ipse cum ceteris testatur Eusebium Historiam suam usque ad tempora liberorum Constantini Magni perduxisse.”

Translation:
“Philostorgius indeed praises Eusebius Pamphili—both for many other things and for his Ecclesiastical History—yet he says that in matters pertaining to religion he went astray, since he supposed that God cannot be known and grasped. He, the impious [Philostorgius says], recounts this error of his, and that he committed other such mistakes. Nevertheless he himself, together with others, bears witness that Eusebius carried his History down to the time of the sons of Constantine the Great.”

(= the line you needed confirming “brought it down to the accession/reign of Constantine’s sons.”)

Socrates Scholasticus testimony immediately below (same page)

Latin (opening):
“Eusebius Pamphili res in Ecclesia gestas decem libris complexus, principatu Constantini Historiam suam terminavit…”

Translation:
“Eusebius Pamphili, having set forth the affairs accomplished in the Church in ten books, brought his History to an end with the principate of Constantine…”

(There follow notices about what he wrote elsewhere concerning the Arian controversy and the imperial orations.)

Jerome / Rufinus items (pp. 69–72 samples)

Latin (Jerome, epistolae & prefaces; compressed):
“Fortissimos libros contra Porphyrium scripsit Apollinaris… ecclesiasticam pulchre Eusebius Historiam texuit… In sex libris, contra Porphyrium… Quis prudentior, doctor, eloquentior Eusebio et Didymo, assertoribus Origenis inveniri potest?”

Translation:
“Apollinaris wrote exceedingly powerful books against Porphyry… and Eusebius beautifully composed the Ecclesiastical History… In six books against Porphyry… Who could be found more judicious, more learned, more eloquent than Eusebius and Didymus, defenders of Origen?”

Latin:
“Eusebius Caesariensis episcopus… in Bibliotheca divina cum Pamphilo martyre conquisita, edidit infinita volumina…”

Translation:
“Eusebius, bishop of Caesarea in Palestine… after assembling, together with the martyr Pamphilus, the divine Library, published countless volumes…”

Latin (re: Daniel/Porphyry polemic):
“Contra prophetam Danielem duodecimum librum scripsit Porphyrius… cui solertissime responderunt Eusebius, Caesariensis episcopus…”

Translation:
“Porphyry wrote a twelfth book against the prophet Daniel… to which Eusebius, bishop of Caesarea, responded with the greatest skill…”

Greek line repeated in the German passage (Brennecke cites Photius’ epitome of Philostorgius 1.2)

Greek:
“Ὅτι τὰ τε ἄλλα … ὁ Φιλοστόργιος τὸν Παμφίλου Εὐσέβιον ἐπαινῶν… καταπαῦσαι δὲ αὐτὸν τὰς οἰκείας τῆς ἱστορίας μνήμας μέχρι τῆς τῶν παίδων διαδοχῆς τοῦ μεγάλου Κωνσταντίνου συνεπιμαρτύρεται.”

Translation:
“That, with respect to other matters and in what pertains to history, Philostorgius—while praising Eusebius son of Pamphilus—says that he went wrong in piety… and he also attests, together with others, that he (Eusebius) brought his own historical record down as far as the succession of the sons of the great Constantine.”

Socrates, HE I.21

“Since certain people too have tried to slander Eusebius Pamphilus—alleging that he was often on Arius’s side in his books—it seems a good moment to speak to the point.
First, it is agreed that he himself was present at the Nicene Council. Secondly, in the third book of his Life of Constantine he uses these words: ‘Let all of us be eager for concord and united in the same opinion, lest through our dissensions we give joy to the adversaries.’
If someone perhaps should think him to have been an advocate of the Arian dogma—which some will judge from those books in which he is accustomed to discuss ecclesiastical matters—let him hear what he says on the dispensation of our Lord Jesus Christ. For he affirms with his own voice that the Son is other than the things that were made, that he was begotten from the Father before the ages, and that, if one prefers, he is God from God; and along with the Father is worshiped by the whole creation.
As to the question whether the Son of God is a creature like the rest of created things, he plainly teaches in the first book of his Preparation for the Gospel (chap. 9) that the Word himself, the Son of God, is not one of the things that came into being. With good reason, therefore, he rebuked Marcellus.”

2. Continuation on the next page (discussion of Prov 8:22 etc.)

“They do not hesitate to say that those who are created are all brought forth from nothing, just as all other creatures are from nothing. But when the Son is ‘begotten,’ when he is ‘Only-begotten,’ he does not share the same nature as the rest of creatures; for ‘only-begotten’ and ‘one among many created things’ cannot mean the same thing. Divine oracles preach not such things.
Soon after he inserts: ‘If someone asks whether the Son of God is of things made or of nothing, it is impious to say he is of nothing, and rash to call him a made thing; for we confess him to be from God, from the Father, not as a product fashioned by an artisan, for the world itself is said to be fashioned by the highest God; the Son, however, is said to be begotten from the Father.’
… Therefore the voice in the Scriptures, Dominus creavit me initium viarum suarum (“The Lord created me as the beginning of his ways”), must be examined with care. Marcellus, indeed, makes one meaning out of this place; but in many works Eusebius Pamphilus shows that the word ‘created’ in Proverbs is set down figuratively (κατ’ οἰκονομίαν), not according to the strict rule and order of truth. He strives in vain who tries to accuse and slander him. Nor can we approve of those who suppose that Eusebius began to teach that the Son was a creature; for in many places he clearly professes that he preaches the Son as God from God, and that he is not reckoned among created beings.”

(Then Socrates cites further authorities and adds a note from Sozomen that Eusebius’ aim was to record the rise of the Christian religion, drawing also on Clement, Hegesippus, and others.)

3. Shorter notices on the later images (select items)

“Victorius in Canone Paschali… Hieronymus in Epistola ad Chromatium…”
“It is agreed that our Lord Jesus Christ wished that the memory of his martyrs be preserved, whose passions we find were recorded by the holy bishop Eusebius of Caesarea. When the emperor Constantine desired that the Church at Caesarea gain benefit from these [records] and that they be set up publicly in the Roman city, he ordered Eusebius to compose, from the archives, a History of the Church and to declare everything in order. This was done; and the most learned historiographer fulfilled the king’s command.”

“Gelasius papa in decreto de libris apocryphis” (paraphrased):
“Not only his Chronicle but also many books of ecclesiastical history Eusebius of Caesarea produced; and at the beginning he composed a certain book against Origen’s schism but later amended it and brought it into proper form.”

Evagrius, HE I.1 (condensed):
“Eusebius Pamphilus, a man outstanding in many matters, was energetic in writing and powerful in speech, so that he could leave useful works to us Christians and embrace many things.”

Gregory the Great to Eulogius of Alexandria (gist):
“It is well known that Eusebius of Caesarea collected the Acts of the martyrs and transmitted them to us.”

Sozomen, Church History I (proem):
“My plan, indeed, was to begin this work right from the very rise of the Christian religion. But when I noticed that other writers— I mean Clement and Hegesippus, most wise men who lived closest after the times of the apostles— and also the historian Africanus, and Eusebius surnamed Pamphilus (a man exceptionally trained both in the sacred writings and in the poets and other profane authors)— had undertaken to write this same subject down to their own times, … I proceeded accordingly].”

(Ellipsis = the line where your image breaks off.)

Image 2 (page headed “VETERUM TESTIMONIA PRO EUSEBIO.”)

Victorius, in the Paschal Canon:
“After reviewing the trustworthy histories of the ancients—namely those of the blessed Eusebius of Caesarea, bishop of the city in Palestine, a man pre-eminently learned and most skilled—together with the prologue of the Chronicle; and since the Chronicle of the blessed Jerome is at hand as well, these have been appended to that same Chronicle.”

Jerome, in the letter to Chromatius and Heliodorus (the letter prefixed to the Martyrology under Jerome’s name):
“It is well known that our Lord Jesus Christ has day by day received the triumphs of His martyrs; and we have found their passions written by the holy Eusebius, bishop of Caesarea. For when the emperor Constantine had entered Caesarea and declared that he wished memorials to be set up for the benefit of the Church by imperial favor, Eusebius is read to have replied that the Church is best enlarged by its own resources and not by subsidies; that his own task was rather to search out with diligent care the public records in the municipal archives and in the city of Rome concerning the deeds done on behalf of God’s saints by judges and the succession of judges throughout the whole Roman world, and to set down who each martyr was, under what judge, and in what province he won the crown. By royal order, therefore, this task was assigned to Eusebius. As a result, since he was a writer of the utmost diligence, he compiled the Ecclesiastical History and declared that he served as historiographer for all the martyrs of the provinces.”

Gelasius, pope, in the decree on apocryphal books:
“Likewise the Chronicles of Eusebius of Caesarea and the books of his Ecclesiastical History—although in the first narration of his account he seems to have inserted certain things that incline toward Origen’s opinions—are nevertheless to be counted among books to be read, for the sake of knowledge, although they are not to be received for establishing doctrine; the tenth book is to be held in greater reverence.”

[Next excerpt, “In the book On the Two Natures.”]
“We ourselves, speaking with one voice and mind, have received what has come down to us from the majority of our teachers; and we faithfully hand on the testimonies of the masters—Clement and others of the ancients, Hegesippus, the most wise, who followed close upon the times of the apostles; Africanus the historian; and Eusebius, surnamed Pamphilus—explaining the Psalms in seven books; and by the same Eusebius the Preparation [for the Gospel].”

(This paragraph is a compressed catalogue; I’ve rendered the sense rather than every abbreviation.)

Page 75 (bottom): Sozomen notice (Latin paragraph beginning “Atque animus…”)

“And indeed the intention was this: that, from the very beginning of the Christian religion’s rise, the matters be carefully observed. But as others before us—Clement of Alexandria, Origen the teacher, and Egesippus, men of great wisdom who lived at the times nearest to the Apostles—handed things down in their own writings, so also did Judas (who was surnamed Thaddaeus), Mark the Evangelist, and Luke the physician compose their own narratives; and among later men also Pamphilus (the fellow-ascetic of Eusebius) wrote in defense of Origen, and Eusebius himself, cognominated Pamphili, wrote books On the Preparation [for the Gospel], On the Demonstration [of the Gospel], and many others, in which he set forth the ancient times with great diligence; and he is recognized as a most exact historiographer.”

Page 77 (top half): Victorius, Jerome, and Gelasius notices

Victorius in the Paschal Canon
“Accordingly, after reviewing the trustworthy histories of the ancients—namely those of the blessed Eusebius of Caesarea, a man most learned and highly instructed—and after adding the Chronicle, marginal notes in Jerome’s hand have been appended to that same Chronicle.”

Jerome, in the Letter to Chromatius and Heliodorus (so titled)
“It is established that our Lord Jesus Christ received daily the crowns of the martyrs; we find the accounts of the martyrs written by Saint Eusebius, bishop of Caesarea. When the emperor Constantine had entered Caesarea and said to the aforesaid bishop that these memorials, if made public, would be of benefit to the Roman commonwealth, Eusebius is read to have replied that, while he judged they would bring no advantage to the Church, yet he had an unshaken desire that the records of the saints be preserved in public monuments; and thus, by the emperor’s command, he arranged that the acts of the martyrs be lodged in the public archives of the Church. By royal order it also came about that Eusebius compose the Ecclesiastical History, and that he declare the deeds of nearly all the martyrs in every province.”

Gelasius, pope, in the Decree on Books
“Likewise the Chronicle of Eusebius of Caesarea and the books of his Ecclesiastical History—although in the first draft of his narrative he had been lukewarm, and afterward, in praising and defending Origen, he composed a book—nevertheless, on account of his singular knowledge of events, we judge are to be read (i.e., permitted to be read).”

(following sentence opening of “De duabus naturis”)
“So that, saying the same thing with one heart and one voice, and believing with unanimous mind, we may hand down to posterity what is to be confessed—together with the supporting testimonies of the masters that are gathered—[there is cited] Eusebius, surnamed Pamphilus, from his exposition on Psalm 7, etc.”

Nicephorus, Hist. Eccl. VII (Latin)

Translation
“At the same time, we know that the godly Pamphilus flourished, a Christian philosopher both in learning and in manner of life, and advanced to the rank of presbyter. His whole life and deeds—together with the renowned school of secular and divine philosophy that he established there, his unwavering confession in the various persecutions, and his contests and outstanding martyrdom for the name of Christ—were fully set forth in a special work by Eusebius, his sister’s son, who was so dear to him that he took his surname from him. To that work we refer those who wish to learn these matters more exactly.
This Eusebius, after mastering every discipline and excelling above all in knowledge of the sacred letters, lived down to the times of Constantius. And since he was most devoted to the Christian profession and breathed a noble zeal for the honor of Christ, he composed the Preparation for the Gospel in fifteen books and the Demonstration of the Gospel in another ten. He himself was the first to put his hand to the present subject, and he was the first to call those books an Ecclesiastical History, which he completed in ten volumes. There is also another of his works, in which he set out a fixed and accurate reckoning of times, and which he called the Canon. He likewise wrote On the Life of Constantine in five books, and published another to the same [emperor] which he entitled the Tricennial. To a certain Stephanus he also wrote another work concerning those matters in the Gospels that are questioned or debated. He left behind other various writings as well, which bring great benefit to the Church. Yet, although such was the man, nevertheless it appears in many respects that he approved Arius’s opinion, etc.”

Page headed “Ex Actis manuscriptis sancti Silvestri papae” (Greek + Latin)
Greek paragraph (summary of Eusebius’s scope)

“Eusebius, son of Pamphilus, when composing his Ecclesiastical History, did not treat in detail each martyrdom separately, since others had already compiled such collections. For in eleven books he recorded nearly all the narratives of the sufferings that took place in every city and district, both of martyrs and of confessors; nor did he pass over women, but he also mentioned that many women displayed manly courage for Christ. He also wrote about the succession of the bishops from the apostle Peter, and he set out the sufferings in their proper order. Of the cities and apostolic sees he made mention—Rome, Alexandria, and Antioch—because of their pre-eminence. He wrote these things in the Greek tongue; and from the whole number of such accounts down to his own time he translated the lives [of the popes], those of holy Silvester, etc., into Latin.”

Latin paragraph beginning “Vetus auctor in Passione sancti Valeriani …”

“The glorious contests of the most blessed martyrs are celebrated for us every year with solemn observance. So that the faith of the people, devoted to the martyrs, might rejoice and be strengthened by their patronage, the historian Eusebius, bishop of the city of Caesarea, produced very learned books, especially on ecclesiastical matters, as much as was announced to him by the divine Spirit concerning deeds and times. In them he recorded, province by province, the cities, places, and towns that obtained the triumphs of the martyrs; what deeds were accomplished; and in what order the chief times of officials were arranged. Although he does not set out in full the sufferings of individual martyrs, nevertheless by brief notices he indicates how they should be truthfully described and commemorated; and he cultivated this [work] so that, like a small measure of wheat, it yielded copious seed in its abundance. Thus, by the account given above and by the faith of the faithful spread throughout the world, the passions of the martyrs everywhere were celebrated and set forth in writings.”

Closing notice “Usuardus in Martyrologio …”

“On the 21st day of the month of June, in Palestine, Saint Eusebius, bishop of Caesarea and confessor, a man of the highest genius and a historian.”

Page 83 (top to mid-page)

(Prayer rubric and notices about offices for St. Eusebius)
“In the Breviary of the Church of Leontini, printed in the year 1587 by Huguetanus Barbou, the collection has on the same day:
‘Almighty, everlasting God, who grantest that the solemnity of blessed Eusebius the confessor and bishop may be celebrated by the highest pontiff: grant that, by his intercession, we may merit to serve Thee in perfect charity. Through our Lord Jesus Christ…’”

Ancient Missal note (Paris, 1483, St-Victor):
“On the day of St. Eusebius the bishop the office is ‘Statuit ei.’ Lesson, Epistle, Gospel. The Gospel: the testimony of God. Evangelium. Watch. The octave of the same is kept on the eighth day of June.”

Old Parisian Calendar:
“In the ancient Parisian calendar the solemnity of the Church is held in the month of June.”

Manuscript title line (Paris MS, on an old office for Eusebius):
“In the name of God, Amen. The office of Saint Eusebius, bishop of Caesarea in Palestine, confessor of the faith…”

From Bede’s De Temporibus (ascribed):
“Eusebius of Caesarea, key to the Scriptures, expositor of the New Testament, much more notable in compiling memorials. We find three works by him which pertain to this volume: four Canons ‘of the Gospels,’ which the New Testament demands be examined; then the books of Ecclesiastical History; and the Chronicle, which we call the breviarium (summary). For though some things are committed to writing by others, we have nowhere found that he himself ever omitted anything.”

From the Miscellanies of ‘Theodorus of Metz’ (cap. 19, incipit quoted in Greek):
A brief notice follows (with the opening Greek words quoted) introducing another short account of Eusebius:

Short biographical note (Latin summary):
“Eusebius, surnamed Pamphilus, from Palestine, a very learned man and of great eloquence, composed many books, and wrote a Life of Pamphilus; he was earnestly devoted to sacred studies; and because he was very well-versed in writings, a man most learned everywhere; and in his works he sometimes seems to have favored Arius; yet afterward he corrected this, as is clear, and he spoke more gently.”

1. Page 85 (heading: Epiphanius on the Meletian heresy; and the note from the Egyptian bishops’ letter)

Epiphanius in haeresi Meletianorum

“At that time the emperor flared up with great anger; accordingly he ordered a synod to be convened at Tyre, and appointed as judge Eusebius of Caesarea, who in the judgment of certain men from Caesarea presided—men who were strongly inclined toward the most impious Arian doctrine. When the bishops from Egypt arrived—subject to Athanasius, whom the adversary bishop had opposed—they were the first to be present, men quite eminent for holiness of life; among them was the very blessed Potamon, bishop and confessor of Heracleopolis. There were present as well the followers of Meletius, the successors of that heresy. The blessed Potamon, a lover of truth, burned with zeal and with the freedom that admits no fear; he never shrank from confessing the truth even in persecution. Now when Eusebius had taken his seat as judge and the trial was beginning, seeing Athanasius standing there he was deeply pained and, in the sharpest indignation and with the sort of invective used in public trials, cried out: ‘Tell me, Eusebius—do you dare to sit in judgment on Athanasius? Is it possible that you, who in the time of the persecution betrayed the truth and mutilated part of your body, should now sit to judge those who confessed? By what means did you escape prison and chains, unless perhaps you promised to sacrifice—or even sacrificed?’”

Ex epistola episcoporum catholicorum Aegypti…

“You know, indeed, as we said above, that for some time our opponents have set themselves against us; and not long ago Eusebius of Caesarea showed hostility toward us as well.”

2. Page 85–88 (headings: Athanasius in the letter On the Decrees of the Council of Nicaea; and Likewise in the treatise On the Synods of Ariminum and Seleucia)

Athanasius in epistola De decretis synodi Nicaenae

“And it is a wonder that although Eusebius, bishop of Caesarea, had previously subscribed, afterwards he withdrew; he revoked his subscription and wrote letters in which he declared that he agreed with the Church and with the tradition of the Fathers. To all he made it manifest that he had not fought against the truth out of shame. Yet, although he wished the decision of the Church to stand, in a certain letter which he sent to the emperor he insinuated—plain enough from his very words—that the Son is not consubstantial with the Father. Moreover elsewhere he openly stated, and thus particularly laid an accusation against the Arians, that the Son of God did not exist before the Incarnation, but only came into existence at the Incarnation.”

Idem in tractatu De synodis Arimini et Seleuciae

“Especially then, what did Acacius—Eusebius’s teacher—reply? He not only denied that he had subscribed at Nicaea, but in a letter to the people he also signified that the faith there set forth was different from the tradition held in common by the Church…” (the passage continues beyond the visible lines).

Idem in tractatu De synodis Arimini et Seleuciae. — “Tell me, then, what will Acacius reply on behalf of his teacher Eusebius? Eusebius not only subscribed to the Nicene synod; he also wrote to his people to declare that the faith set forth at Nicaea by common consent is the true one. In that letter he may have gone further than I would like, but he did not repudiate the council. He even charged the Arians with impiety for saying ‘the Son was not before he was begotten,’ since he himself affirmed that the Son existed before his birth from Mary.”

Idem in epistola ad episcopos Africae. — “Nor is anyone unaware of Bishop Eusebius of Caesarea. Though at first he lent his vote to the Arian party, later he subscribed to the decrees of the Nicene council; and in his own books he wrote and confirmed many things which he had previously been reluctant to acknowledge, including, when speaking of the Father and the Son, the use of the term ‘consubstantiality.’”

Idem in tractatu De synodis Arimini et Seleuciae. — “Eusebius also of Caesarea in Palestine, in letters to Bishop Euphration, is said to have declared that Christ is not a true [God/Deity] …” (the sentence on the scan breaks off at this point).

Hieronymus in epistola ad Ctesiphontem adversus Pelagianos. — “He had already done this in the first book of the Defence of Origen, where—under the name of the martyr Pamphilus—he put forward Eusebius of Caesarea; but immediately upon weighing anchor and leaving port he ran his ship aground, for he produced from that work not Pamphilus the martyr but Eusebius, the leader of the Arians.”

Idem in libro secundo adversus Rufinum. — “Eusebius of Caesarea, the bishop whom I mentioned above, in the sixth book of the Apology for Origen brings this same charge against Methodius the bishop and martyr, namely that, among his many praises of Origen, he dared to ask: ‘How could Methodius attack Origen’s dogmas when he himself is so thoroughly Origenist?’ Not that the charge was my own invention; rather, it is found in many places in their writings. Now at last let him be satisfied, since I praise the most illustrious and eloquent martyr Arius’s only foe no more, lest I be thought a friend of his praises and an enemy to his successes.” (Sense preserved; the rhetoric is barbed in the Latin.)

Socrates, lib. i, Historiae ecclesiasticae, cap. 35. — “Eusebius, the son of Pamphilus, wrote down the affairs of the Church in ten books, bringing the narrative down to the times when the Egyptian synod’s disturbances arose, adding nothing beyond this. And since in two languages (Greek and Latin) it may come under suspicion, for that reason I omit to relate at length what came afterwards, because it was not fitting to foist in what was decreed at Nicaea.”

Theodoretus in interpretatione Epistolae Pauli ad Hebraeos, de Arianis loquens, ita scribit: — “On this point alone it is sufficient and persuasive that Eusebius, bishop of Caesarea in Palestine, wrote that he himself had suffered many hardships on account of Origen; and yet he calls the dogmas of his own teachers ‘patristic’ [i.e., of the Fathers].”

Antipater Bostrorum episcopus in libro primo Adversus Eusebii Apologeticum pro Origene. — “Yet I am not silent about how the doctrine of the Church was perverted by Eusebius, who mixed together the glory of learned doctrine with profane opinions. To him some things are allowed; but not the rest. Rather, I will strive the more carefully to present an accurate account of many matters, lest, as he himself says, ‘many things being unknown to us,’ we be deceived; for after Eusebius of Pamphilus had written at length in defence of Origen, I undertook to write against him.”

Page 89 (right column)

From the synod convened at … (context: after Nicaea):
“Who among the faithful of the Church, after they had embraced the true and saving doctrine, could be ignorant that Eusebius of Caesarea (called ‘Pamphilus’), once he had been convicted by our judgement, subscribed? In truth, he was afterwards again found in the writings of those who had adopted the Arian impiety, and he was seen sitting with them in council and issuing judgement. If he had truly contemplated Athanasius face to face, he would have been overcome with grief; but since he was of the same temper as those men, a torrent of insults burst forth from his mouth. And so, Tenes (i.e., ‘then’), it is said, Eusebius, sitting, condemned Athanasius as a judge. Who could bear such shamelessness? For my part, I would rather be a fugitive, innocent though I am, than sit as judge over the truth. And so I, a poor exile for the truth, have lost my homeland, and, lacking my bodily freedom, I endure the hardships of martyrdom; but your master’s shamelessness consists in this: that he escaped the sword and prison because he had been ready to sacrifice—or perhaps had even sacrificed.”

From the letter of the Catholic bishops of Egypt and the Synod of Tyre (cited by Athanasius):
“And what is amazing: even though Eusebius, bishop of Caesarea in Palestine, had signed only under compulsion at first, he later sent a letter in his own hand in which he openly declared that he had accepted the Nicene faith as the Church desired. Yet in a letter he wrote later to Paulinus he insinuates, quite openly, that the Son does not share the substance of the Father, which he indicates by the very words. And finally, again he accuses the Arians’ opponents of ignorance, saying that they do not understand that the Son of God existed before time, although he denies—not only before his birth according to the flesh, but even in any way—that He existed before the Incarnation.”

Page 90 (right column)

“Let us pass over the earlier things; we have learned enough. And a little later: We may seem to wrong him by heaping insults; but it is not our purpose to insult, rather—as apologists—we examine and test both sides, whether heresy is to be extended from this man, or whether the appearance of such things, once torn away, reveals a defence taken up. And a little further on: When he quotes certain sayings against Origen, he proves neither the Son’s relation to the Father, nor the claim that the Son was created; he merely utters words that are altogether ridiculous. From this man you will often hear things of the same sort. Thus from this heap of the most noble names let a conclusion be drawn. At any rate, the aforesaid matter has now been sufficiently exhibited.”

From the Acts of a universal synod (on investigation …):
“… (summary:) Eusebius of Caesarea is rebuked for glossing his own historical books in favour of the Word (Logos) of God as he understood Him—yet in council he subscribed (to Nicene), later he withdrew; now praising one party, now another, according to the times; sometimes lauding those who think like Arius, sometimes, when it suited, the others; he appears double-minded and, as Jacob the brother of the Lord says, ‘unstable in all his ways’ before the Lord. If he had trusted in righteousness and confessed the truth unto salvation, he would have ceased from vain writings; but he stayed like an Ethiopian with unchanged skin. Finally, when he is heated up, he says: ‘The Lord created me the beginning of His ways’—and from this he infers that the Son who was begotten is a creature; thus he says that the Son is God and Lord together with the Father, and yet he also says that He is a creature.”

“And again in a letter to the holy Alexander, he writes in the very same sense … (then a string of proof-texts are adduced, e.g., Prov. 8:22, Ps. 2, etc.) … If therefore the Son was before the ages as God’s Word—for thus he tries to argue—why does he at the same time call Him a creature? … ‘This is the chief occasion for blasphemy,’ he says, ‘that the Son is said to have been made’ …”

“And further he writes: ‘I and the Father are one’ (and he twists even this to suit his purpose) … And a little later: ‘My Father is greater than I’ … And afterwards: ‘No one has seen God at any time’ … From these he attempts to show that the Son is less; but in fact he rather betrays his own ignorance; for the true faith teaches otherwise.”

From Athanasius, in the letter to Constantius the Emperor:
“Eusebius, the servant of Pamphilus—your friend, our enemy—was infected with Arianism. He wrote these books not on our behalf but against us.”

p. 91 — Idem Photius in Bibliotheca, cap. 15

“I have read two books of Eusebius that are entitled Refutation and Apology. In many places they differ from his earlier works; in religion, however, they keep the same sense and position. He meets the objections of his opponents against our holy religion very correctly and, for the most part, satisfactorily. His diction, though not elegant, is clear and not unpleasant to read. Because of the great number of chapters, the treatment is not very concise; yet his prudence and his constancy in doctrine do not allow the truth to suffer. In those books of his he censures the blasphemers against the Son and attributes the rise of the Arian evil to the Prince of this age, the leader of the heavenly host. It is agreed that he flourished in the times of Constantine the Great; and he is said to have been bound by an ardent love for the holy martyr Pamphilus, whose disciple he was.”

p. 92 — Idem Photius in (Bibliotheca) cap. 127

“I have read four books of Eusebius Pamphilus On the Praises of the Emperor Constantine. He also wrote The Life of Constantine, in which from the very beginning he recounts everything to old age, and whatever was done by him both in public and in ecclesiastical matters, as far as the end of his life, finishing the fourth book at the year when he received baptism; and this same book he brought to an end in that very year. I have also read his Ecclesiastical History in many books, in which he set down the succession of bishops from the time of the apostles, and related the most noteworthy events of the Church, and the conflicts and heresies that arose, down to our own times. In these same books he often mentions Arius and makes no concealment of his [i.e., Arius’s] heresy. He also records the baptism of Constantine, stating who baptized him and where. Likewise he does not pass over in silence the things that concern Arius.”

This is interesting because he can't be referencing any of our known texts listed above as VC certainly does not name who baptized Constantine:
At first he experienced some slight bodily indisposition, which was soon followed by positive disease. In consequence of this he visited the hot baths of his own city; and thence proceeded to that which bore the name of his mother. Here he passed some time in the church of the martyrs, and offered up supplications and prayers to God. Being at length convinced that his life was drawing to a close, he felt the time had come at which he should seek purification from sins of his past career, firmly believing that whatever errors he had committed as a mortal man, his soul would be purified from them through the efficacy of the mystical words and the salutary waters of baptism. Impressed with these thoughts, he poured forth his supplications and confessions to God, kneeling on the pavement in the church itself, in which he also now for the first time received the imposition of hands with prayer. After this he proceeded as far as the suburbs of Nicomedia, and there, having summoned the bishops to meet him, addressed them in the following words.

Chapter 62. Constantine's Appeal to the Bishops, requesting them to confer upon him the Rite of Baptism.
The time is arrived which I have long hoped for, with an earnest desire and prayer that I might obtain the salvation of God. The hour has come in which I too may have the blessing of that seal which confers immortality; the hour in which I may receive the seal of salvation. I had thought to do this in the waters of the river Jordan, wherein our Saviour, for our example, is recorded to have been baptized: but God, who knows what is expedient for us, is pleased that I should receive this blessing here. Be it so, then, without delay: for should it be his will who is Lord of life and death, that my existence here should be prolonged, and should I be destined henceforth to associate with the people of God, and unite with them in prayer as a member of his Church, I will prescribe to myself from this time such a course of life as befits his service. After he had thus spoken, the prelates performed the sacred ceremonies in the usual manner, and, having given him the necessary instructions, made him a partaker of the mystic ordinance. Thus was Constantine the first of all sovereigns who was regenerated and perfected in a church dedicated to the martyrs of Christ; thus gifted with the Divine seal of baptism, he rejoiced in spirit, was renewed, and filled with heavenly light: his soul was gladdened by reason of the fervency of his faith, and astonished at the manifestation of the power of God. At the conclusion of the ceremony he arrayed himself in shining imperial vestments, brilliant as the light, and reclined on a couch of the purest white, refusing to clothe himself with the purple any more.

Chapter 63. How after his Baptism he rendered Thanks to God.
He then lifted his voice and poured forth a strain of thanksgiving to God; after which he added these words. Now I know that I am truly blessed: now I feel assured that I am accounted worthy of immortality, and am made a partaker of Divine light. He further expressed his compassion for the unhappy condition of those who were strangers to such blessings as he enjoyed: and when the tribunes and generals of his army appeared in his presence with lamentations and tears at the prospect of their bereavement, and with prayers that his days might yet be prolonged, he assured them in reply that he was now in possession of true life; that none but himself could know the value of the blessings he had received; so that he was anxious rather to hasten than to defer his departure to God. He then proceeded to complete the needful arrangement of his affairs, bequeathing an annual donation to the Roman inhabitants of his imperial city; apportioning the inheritance of the empire, like a patrimonial estate, among his own children; in short, making every disposition according to his own pleasure.

Chapter 64. Constantine's Death at Noon on the Feast of Pentecost.
All these events occurred during a most important festival, I mean the august and holy solemnity of Pentecost, which is distinguished by a period of seven weeks, and sealed with that one day on which the holy Scriptures attest, the ascension of our common Saviour into heaven, and the descent of the Holy Spirit among men. In the course of this feast the emperor received the privileges I have described; and on the last day of all, which one might justly call the feast of feasts, he was removed about mid-day to the presence of his God, leaving his mortal remains to his fellow mortals, and carrying into fellowship with God that part of his being which was capable of understanding and loving him. Such was the close of Constantine's mortal life. Let us now attend to the circumstances which followed this event.
And it's not just that there is the description of Arius. VC only makes passing reference to Arius not the comprehensive treatment referenced in Photius. The most natural reading is that Photius is pointing to the (longer) Ecclesiastical History, not (just) the Vita Constantini:

1. Immediate antecedent in the Greek. In (cod. 127), Photius lists Eusebius’s works and explicitly mentions an ἱστορία ἐκκλησιαστικὴ πολλῶν βιβλίων (“an ecclesiastical history of many books”). The next clause begins with a plural deictic (“in/among these books …”), which syntactically leans toward the immediately preceding plural “many books” rather than the four-book Vita.

2. Content fit. The two specifics Photius gives—(a) “he often mentions Arius and does not keep silent about what concerns him,” and (b) “he records Constantine’s baptism, saying who baptized him and where”—fit a church-history dossier far better than our Vita. In the Vita, Arius is at most incidental, and the officiant of Constantine’s baptism is not named.

Explains the mismatch with our VC. Since VC doesn’t name the baptizer, Photius’s wording is best explained if he’s summarizing what he read in (or attached to) a fuller/extended Ecclesiastical History tradition—one that (per later witnesses) carried the story down into the Arian controversy and the emperor’s baptism.

So, the “in these same books” clause is most coherently taken as referring to the many-book Ecclesiastical History Photius has just cited, not narrowly to the Vita Constantini.

“As for the Arian sect, he does not report anything clearly—neither whether Arius had once adhered to it and later rejected it, nor that he had changed sides, nor even that he had been reconciled in friendship (though he had reason to record such things, since a large part of the great deeds of Constantine has to do with councils, and people will naturally want a very detailed account of these matters). He does, however, recount the dispute that arose between Arius and Alexander (for so they say and covertly decide the matter), and how the emperor was deeply distressed at the schism and labored very earnestly—both by letter and through Hosius, the bishop of Corduba—to bring the parties into friendship and concord, to put an end to the civil strife, and to settle by common agreement the questions that had been raised. At his command, therefore, synods were everywhere convened, and those who had been embroiled were restored to peace.

Nor, moreover, does he pass over in silence the Antiochene synod and what followed it, but he says in so many words that the imperial power, together with those engaged in the inquiry, tried hard to secure an equitable settlement. He also tells how, although the Arians had been publicly condemned by the synod, they did not at first submit to justice; yet not long afterward, seeing God’s judgment, they perished by an evil end. None of these things, however, does he explain in detail in that same history of the council; rather he inserts them elsewhere in his narrative. From this one can see that he has written more fully about the case of the blessed Eustathius—about the accusations that were made, the name involved, the deposition that ensued, and the commotion and disturbance which were afterward transferred into peace by the emperor’s zeal and cooperation.

Likewise, when Athanasius (who was persecuted more than any) takes up these stories in his own writings, he too recounts seditions, disturbances in Alexandria, and the presence of bishops, together with the coming of the imperial authority, and alliances of the parties; yet he does not say who began the sedition, or who did the deeds that were done, or on which side the right lay. And almost always, when he reports quarrels about doctrines or disputes about other matters with other men, he preserves the same method in his narrative.”

Ἰωάννης Ζωναρᾶς ἐν τόνῳ ΙΙΙ, τὰς ἐπὶ Κωνσταντίνου πράξεις φησίν·
“John Zonaras, in Tome III, when he relates the deeds under Constantine, says:”

Latin paragraph (translation)

“Eusebius Pamphili, bishop of Caesarea in Palestine, also embraced Arius’s party; but afterward he is said to have withdrawn from the Arian opinion and to have agreed with those who teach that the Son is co-eternal with the Father and of the same nature; and he was received into the communion of the holy Fathers. In the Acts, at the beginning, he is first defended as a man of holy life. These things are found written by some (sources), but he himself presents them more ambiguously in his Ecclesiastical History. In these books he is accused of siding with Arius. And at the very beginning of the book, while citing David, he himself says—and approves as sound—the words, ‘the things that are commanded and created’; and he calls the Father ‘maker,’ as the founder and ruler of the whole universe, who governs with secure dominion; next after him [he places] the divine Word, to follow the commands of the Father. Again, after the section ‘On the Names’ he says that Power and Wisdom—which had previously held the first rank of power—later yielded the second place, as if in an imperial census, to the rule over all. And a little later again: that God alone is the maker of things and the Lord of humankind; and that, when the divine [Word] lived and subsisted together with him, it acted as minister to God the Father of all in the making of things. For he says this, under the persona of the Wisdom of God: ‘The Lord created me the beginning of his ways,’ etc. Then, after many other statements, he adds as follows: since the Word—which existed before and before all ages—was begotten of God the Father according to its own nature, it is to be worshiped as God. These and other points show that Eusebius was no fool; although there is no title of grace apparent in this work, just as in his other books. Not without cause did he write at length—indeed in four books—about his Ecclesiastical History at Nicaea. And he conceals that Constantine the Great, after the conclusions at Nicaea, delayed baptism and was later baptized; he conceals who baptized him. Moreover, he nowhere openly recounts the Arian heresy.”

John Zonaras is clearly responding to Photius's claims about the Ecclesiastical History. Photius (c. 810–893) is two-plus centuries earlier than John Zonaras (active c. 1118–1140s). Zonaras worked in Constantinople and, after retiring as an imperial official, became a monk with access to major libraries. Photius’ works (especially the Bibliotheca and his lexicon) circulated in Byzantium and influenced later compilers.

Baronius ad annum Christi 310, cap. 38.

Indeed, Socrates later brings in the ‘Ethiopian,’ while he tries to excuse Eusebius himself from the Arian heresy and make him altogether free of it. For he says that Eusebius, although at length he subscribed to the Council of Nicaea in order to oblige the emperor, thereafter kept returning to the same foul opinions and disgraceful defilements, not that he was rolling in the mire like a dog and returning to his own vomit, but that in a certain way he kept slipping back as often as he had occasion; and that after Nicaea he recited the same shameful things. But when a quarrel later arose between Alexander and Arius about a certain statement concerning the Son of God—namely, whether he were a creature, taking a beginning from things created, or whether he were from nothing created by God—then, as soon as Eusebius began to defend Arius, the gravest suspicion of heresy clung to him. And so, both by a letter and by his book, he labored greatly on behalf of Hosius, bishop of Corduba, so that through him the princes might be led to a settlement and concord, and that all questions of that sort might be brought to an end. But he did not bring it to an end; rather, after the tumult of the synod, he continued obstinately in his own opinion. From this point on, we see in him nothing like sound judgment. A little later, with shame laid aside, he openly took up the cause of Arius, carrying on hostile proceedings in synods against the bishops who resisted him; and when Arius, because of his impiety, had deservedly been decreed to go into exile, Eusebius labored with every effort to have the penalty remitted for him. Finally, the infamous recall of Arius—known to all—was achieved through Eusebius’s efforts; and he commemorates those deeds in his writings. From this time, therefore, when he joined himself to that man Eustathius, it is clear what he was able to write, though he did not even dare to give his name to the book, nor did he openly set down in writing the things he perpetrated against us; but, after he said that there was sedition at Antioch, he falsely reports that afterwards there was tranquillity. He claims there was peace, as if the bishops’ works and the emperors’ actions had everywhere brought concord to the whole world and that, after all the disturbance, peace had been restored. Likewise, in the narrative that he inserts about the very violent storm at sea brought on by the emperor’s anger, he relates how the emperor punished Alexander; and he says that a certain bishop, for not obeying the emperor, was cast out of his see. Nor, in the meantime, did he let that sedition die down, since he adds that by agreement there was a mutual laying-on of hands among the bishops. And he often says that there were changes in the bishops as to heads of faith or that dissensions arose among the rest about the definitions of doctrine; he preserves the same man Eusebius as the narrator in a dissembling manner.

Scaliger, in Elenchus Trihaereseos, ch. 27
“Eusebius—who wrote many volumes of ecclesiastical history on behalf of Christianity—left more errors in his writings than anyone; no trafficker in fictions today has palmed off more hallucinations, etc.”

The same, in De emendatione temporum, bk. 1, at the end
“How much greater is the credit due a careful judge than to works produced in great haste—works in which the writings of others are not read attentively. Before long a more learned reader will recognize how much of what the reader gathers under Eusebius’s judgment has in fact been collected from others. For we are dealing only with Eusebius’s mistakes, which he himself, by his manner of writing, has shut off from everyone. And so you will come to know Eusebius, as we all will.”

The same Scaliger, Animadversiones ad Chronicon Eusebianum, p. 8, rebuking Jerome’s words (“how Eusebius, the author of this book, could not have been ignorant, seeing he was most learned”):
“If ‘most learned’ is what we call the man who has read many things, no one can grudge him that praise. But the most learned is the one who has joined sound judgment to reading—something Eusebius rather ought to have supplied.”

Greek (bottom item)

Suidas, s.v. Διόδωρος (Diodoros)
“Diodoros, a monk, who under Julian and Valens became bishop of Tarsus in Cilicia. He wrote various treatises (as Theodoret the Reader reports in his Ecclesiastical History); and there is also a work entitled Chronicon, in which he corrects Eusebius Pamphilus concerning an error in chronology.”

1. Passages that show “Eusebius was an Arian”

The strongest evidence here is from Jerome, Athanasius, the Egyptian synod material, Epiphanius, Zonaras, and the anti-Origenist tradition. The especially useful ones:

a) Jerome’s explicit “Eusebius is an Arian” statements

Letter 65 (to Pammachius and Oceanus): “Apollinaris wrote exceedingly strong books against Porphyry; Eusebius composed the Ecclesiastical History. But the former introduced a ‘halved’ dispensation of Christ, while the latter is the most open champion of the impiety of Arius.”

Apology against Rufinus: “He—Eusebius, bishop of Caesarea—wrote six books on behalf of Origen (as I have already said), being formerly of the Arian party… and, in the Catalogue… he is an Arian.”

Let's say Jerome is our anchor witness that, in the Latin West, Eusebius was remembered not as a neutral chronicler but as “the most open champion of Arius.”

b) Athanasius and the Egyptian material (double-minded, Nicene signature, then relapse)

There are a series of passages (grouped around the “De decretis,” “De synodis,” the letter to the African bishops, and the Egyptian synod letter) that paint a very clear arc. The story here is that he (i) first subscribes at Nicaea “under compulsion,” then sends a letter saying he accepts the Nicene faith “as the Church desired,” but (ii) later, in letters to the emperor, to Paulinus, to Euphration, he insinuates that the Son is not consubstantial and even that Christ is “not a true God,” he is said to have been “at first of the Arian party,” then to have subscribed, then to have slipped back.

c) Epiphanius / Meletian dossier: Eusebius as moral coward and Arian-leaning judge.

Epiphanius’s Meletian passage gives a sharp character sketch: Eusebius presiding at Tyre, regarded by some as a partisan of “the most impious Arian doctrine,” and Potamon throwing in his face that he escaped persecution by compromising. That’s not just “doctrinally suspect”; it frames him as exactly the sort of man who would trim his narrative to please Constantine and the Arian court.

d) Antipater of Bostra & anti-Origenists

Antipater: Eusebius “perverted the doctrine of the Church,” “mixed learned doctrine with profane opinions,” and had to be answered with a counter-history. That gives a late antique precedent for rewriting Eusebian narrative specifically because of his theology.

e) Zonaras’ summary

Zonaras (relying on earlier material, and pretty obviously reading Photius and/or Socrates) says: (i) Eusebius “embraced Arius’s party” (ii) afterward he is said to have recanted in order to be received into communion; in his Ecclesiastical History he presents things ambiguously, is accused of siding with Arius, treats the Son as “created” via Prov 8:22, and so on. Zonaras is post-Photius, but he neatly packages the older charges in exactly the way we want: Eusebius’s history as Arianly slanted.

2. Passages that help most on “Eusebius extended the Church History down to Constantine’s death / sons / baptism”

Here the key witnesses are Philostorgius (via Photius), Photius’s own cod. 127, the Silvester-Acta excerpt (“in eleven books…”), Socrates, and the notices that contrast 10 books with “many books.”

a) Philostorgius via Photius: “down to the time of the sons of Constantine the Great." The Philostorgius excerpt is absolutely central:

“Philostorgius… praises Eusebius Pamphili… Nevertheless he himself, together with others, bears witness that Eusebius carried his History down to the time of the sons of Constantine the Great.”

That gives us a direct claim that “his history” extends to the sons, i.e. beyond the point where our 10-book HE, as normally read, stops. It dovetails perfectly with the thesis that there once existed an extended “Constantinian/Arian” finale. This is the passage we should keep citing as Exhibit A every time we talk about an “extended HE tradition.”

b) Photius, Bibliotheca 127: “in many books” + Arius + Constantine’s baptism naming the baptizer.

Photius in cod. 127 says:

he has read four books of the Praise of Constantine; he has also read the Ecclesiastical History “in many books”; in these same books Eusebius “often mentions Arius” and “does not pass over in silence the things that concern him”; and he “records the baptism of Constantine, stating who baptized him and where.”

Two crucial points is that “In many books” is not restricted to the four-book VC. In fact, the natural grammatical antecedent is the “many-book” Ecclesiastical History just mentioned. In our extant HE, we do not have a detailed account of Constantine’s baptism with the officiant named, but Photius says he read such a thing in Eusebius. That strongly favors the claim that there was, at some stage, a church-history text (or HE + continuation) that covered both Arius and Constantine’s baptism in greater detail than our HE + VC now do. We can argue:

(i) Either Photius had a longer HE (my thesis),
(ii) Or he is conflating HE and some other lost work which still implies a Eusebian historical treatment down to Constantine’s baptism where Eusebius's baptizer is named (as in Philostorgius's source = longer HE).

What argues for interpreting Photius arguing from HE these point is his descendant in Byzantium John Zonaras:

Photius: “I have also read his [Eusebius’s] Ecclesiastical History in many books … In these same books he often mentions Arius and makes no concealment of his heresy. He also records the baptism of Constantine, stating who baptized him and where.” Zonaras: Treats “these books” as the Ecclesiastical History, not the four-book VC: “he himself presents them more ambiguously in his Ecclesiastical History. In these books he is accused of siding with Arius…” He is clearly reading Photius as if the Arius/baptism material belongs in a (longer) HE.
Photius on Arius: HE “in many books” where Eusebius “often mentions Arius and makes no concealment of his heresy… Likewise he does not pass over in silence the things that concern Arius.” Zonaras on Arius, reacting to that: “In these books he is accused of siding with Arius… he nowhere openly recounts the Arian heresy.” Zonaras expects, from Photius, a full Arian dossier in HE; not finding it in his text, he complains that Eusebius is evasive.
Photius on Constantine’s baptism: still referring to the “many-book” HE, he adds, “He also records the baptism of Constantine, stating who baptized him and where.” Zonaras on Constantine’s baptism, clearly answering Photius: “And he conceals that Constantine… delayed baptism and was later baptized; he conceals who baptized him.” Zonaras only writes this because he has read Photius as claiming that HE explicitly named the baptizer and place—and his own HE copy does not.
Correct reading of Photius: the natural grammatical antecedent of “in these same books” is the “Ecclesiastical History in many books”; Photius places the detailed Arius material and the named-baptizer account inside a multi-book HE, not in the four-book VC. Zonaras’ dependence confirms that reading: he assumes Photius meant a longer Ecclesiastical History containing explicit Arian narrative and baptismal details, and measures his shorter, more ambiguous HE against that expectation. Zonaras thus witnesses to a reception of Photius in which Photius is understood to attest a HE longer and fuller than the text Zonaras actually has.

c) The Silvester-Acta Greek notice: “in eleven books he recorded nearly all the narratives…”

The Greek notice about Eusebius in the Silvester Acta says that “in eleven books he recorded nearly all the narratives of the sufferings… and the episcopal successions” etc. Even if we don’t press the exact number (“eleven”), the important bit is that some ancient tradition counted more than ten “books of ecclesiastical history” under Eusebius’s name. Combine this with Philostorgius’s “down to the sons” and Photius’s “in many books” and you have a cluster of independent hints that the “ten books” we have are not necessarily the whole story.

d) Socrates: 10 books to Constantine + he stops short of Nicaea narrative

There are two useful things out of Socrates: (i) The formal line: “Eusebius Pamphili… in ten books brought his History to an end with the principate of Constantine…” Then the explanatory note that he omits the later Arian quarrels and Nicene decrees because it would not be fitting to repeat them, and that others (including himself) will take up those matters. This can be argued to be:

Socrates knows a ten-book Eusebius ending at Constantine, but he also knows there are further Eusebian discussions of the Arian controversy and councils (which he is choosing not to reproduce fully), so he draws his own cutoff.

This gives us room to say: there was pressure even in Socrates’s time to limit how much Eusebian material on Arian disputes got passed on in “ecclesiastical history” proper.

e) Nicephorus / later biographical note

Nicephorus’ summary that Eusebius “wrote the Ecclesiastical History in ten volumes” but also a separate Life of Constantine in five books and a Tricennial is standard. For our purposes it mainly helps to show that later readers “unbundled” his Constantinian history into parts (HE, VC, Tricennial, etc.), which makes it easier to imagine portions being dropped or reassigned.

3. Passages that support “the extension was later removed / corrected”

Here we want anything that shows:

(i) awareness of multiple drafts / corrections of Eusebius’s works,

(ii) caution about some parts vs others (e.g. Book 10),

(iii) explicit accusations that he glossed or concealed facts in his histories,

(iv) and a tendency of later writers to re-frame him so he looks more orthodox.

Especially helpful are:

a) Gelasius on Eusebius’s Chronicle / History: allowed to be read, but with doctrinal caveats, “tenth book in greater reverence”

The Gelasian decree says roughly:

"the Chronicle and the Ecclesiastical History of Eusebius are to be read for knowledge, though not for establishing doctrine;

in the “first narration” he inserted things inclining toward Origen;

later he “amended” or “brought it into proper form”;

and the tenth book is to be held in greater reverence."

This is almost tailor-made for the “corrected / pruned” thesis. It gives us:

A patristic statement that there were at least two states of Eusebius’s historical work;
An explicit hierarchy among the books (the 10th being somehow safer / better regarded);
A precedent for editorial intervention in Eusebius motivated by theology.

We can easily extend that logic: if Origenist material triggered “amendment,” so too could overtly Arian material in a Constantinian finale.

b) The synod/Acts passage: Eusebius accused of glossing his own historical books and being “double-minded”

The Acts excerpt is dynamite:

It says he “glossed his own historical books” in favor of his (Arian) understanding;

that he sometimes praises Arians, sometimes their opponents, “according to the times”;

that he hides or twists facts (e.g. Prov 8:22) to make the Son a creature, while still calling him God and Lord;

and that he is “unstable in all his ways.”

This gives us direct testimony that:

Eusebius’s historical books were perceived as doctrinally tendentious;

Later ecclesiastical authorities saw a need to expose and correct those glosses.

We can argue that one way this “correction” happened was precisely by dropping or re-editing the most problematic sections—i.e. an Arian-tilted Constantinian ending.

c) Photius’ comparison of “Refutation and Apology” vs earlier works

Photius says:

he read two books of Eusebius entitled “Refutation and Apology”;

they differ in many respects from his earlier works,

but keep the same religious sense;

in them he censures blasphemers against the Son and attributes Arian evil to the devil.

For this thesis, the value is not so much “Eusebius = orthodox” (Photius wants to rehabilitate him) but the awareness of multiple layers in Eusebius’s oeuvre—earlier, dodgier material, and later “apologetic” self-presentation. That pattern matches the hypothesis of earlier Arianizing history + later bowdlerized version.

d) Zonaras’ charge that he “conceals” things and never openly recounts the Arian heresy

Zonaras explicitly says that in his Ecclesiastical History Eusebius:

“conceals that Constantine delayed baptism and who baptized him,”

“nowhere openly recounts the Arian heresy,”

and treats much of the doctrinal turmoil in a veiled way.

Zonaras is trying to excuse Eusebius (“he was no fool”) but in doing so he gives us a perfect rhetorical handle: a tradition that Eusebius’s history, as available to Byzantines, had already been “cleaned up” and was no longer straightforward about Arian matters.

If there had once been a more explicit Constantinian/Arian ending, Zonaras’s complaint that the available text “conceals” things is exactly what you’d expect if that ending had been rewritten or lost.

e) The repeated theme that Eusebius’s writings were “corrected,” “amended,” or needed a counter-history

Between:

Gelasius’s “first narration… later amended,”

Antipater “undertook to write against him” to correct his distortions,

Diodorus (per Suidas) writing a Chronicon to “correct Eusebius Pamphilus concerning an error in chronology,”

Scaliger and later critics cataloguing “Eusebius’s mistakes,”

we can make a broad case that Eusebius’s historical authority was always treated as something to be curated and, where necessary, purged or supplemented.

That gives the specific hypothesis (pruning an Arian Constantinian ending) a natural habitat: it’s not some unprecedented conspiracy, it’s just one more instance of the Church managing a problematic but indispensable historian.