Eusebius was the friend of Constantine, and he wrote, in part, to affirm the new Church-State relationship that Constantine had established.  That new Church-State relationship was antagonistic to the expected kingdom of God that had been proclaimed by the apostles.  In the new relationship, the Church would establish the kingdom of God through the State.  Once this new relationship was accepted, it became necessary to change the expectation of what the kingdom of God would be. "The overwhelming usage of 'kingdom' in the second-century Christian literature is eschatological," 1 that is, the second-century Christians expected the establishment of the kingdom of God to come with the return of Jesus at the end of the age.  They understood that there was a sense and a reality in which the kingdom of God was already present, but its fulfillment would only come with the destruction of the kingdoms of this world.
"With Origen in the early third century there arose a thinker who was able to incorporate the 'Gnostic' dimension of the kingdom, the inward rule of God in the soul, into orthodox thought...Origen thus marks the turning point." 2  In this Gnostic view, the fulness of the kingdom of God was to come with the individual believer's spiritual growth, and with the spiritual growth of the Church as a whole.  The return of Jesus to judge the nations and to redeem Israel became unnecessary for the establishment of the kingdom throughout the earth.
With the introduction of Origen's allegorical method of interpretation in the third century, the faith of the Church concerning the kingdom began to change.  As the anti-Judaic posture spread in the Church, what was once considered heresy was put forward as the new orthodoxy.  The Millennial restoration of Israel began to be considered a carnal, Jewish doctrine which no orthodox Christian could believe.
On different issues in his Ecclesiastical History, Eusebius often quotes from earlier writers in the Church who embraced views similar to his own.  That is natural and acceptable for any writer who seeks to support and establish his own views.  On the issue of a literal, Millennial restoration of the kingdom to Israel - THE theological issue on which the new Church-State relationship would stand or fall - Eusebius does not quote from any in the early Church who embraced his own view.  He does not because he cannot.  There were none who supported his view.
Eusebius shows that he had early Church writings on this issue.  But these writings expressed a faith in a literal, Millennial restoration of the kingdom to Israel.  Since Eusebius rejected that view, and because he wanted to brand it as heresy, he chose not to quote from any of the early Church writers at all.  So it is understandable that those who accept the writings of Eusebius as an accurate representation of the theology of the early Church tend to believe as he did.  Unfortunately, Eusebius is not faithful in this regard.
Eusebius happens to reveal, albeit quite reluctantly, that the "new Israel" view which he embraced was not held by the apostles or by those who were instructed by them.  One such student of the apostles was Papias who was taught by the Apostle John, by Philip the evangelist (Acts 21:8), and by others.  He was an associate of Polycarp.  In one section, Eusebius says, "At this time, also, Papias was well known as bishop of the church at Hierapolis, a man well skilled in all manner of learning, and well acquainted with the Scriptures." 3  Throughout the Ecclesiastical History, with one exception, and in the writings of all others who spoke of him, Papias is characterized as a very godly man of exceptional learning, faithful to the teachings of the apostles.  The one exception occurs when Eusebius mentions that "he [Papias] says there would be a certain millennium after the resurrection, and that there would be a corporeal reign of Christ on this very earth; which things he appears to have imagined, as if they were authorized by the apostolic narrations, not understanding correctly those matters which they propounded mystically in their representations.  For he was very limited in his comprehension, as is evident from his discourses; yet he was the cause why most of the ecclesiastical writers, urging the antiquity of the man, were carried away by a similar opinion; as, for instance, Irenaeus, or any other that adopted such sentiments." 4
Several things should be noted about Eusebius' comments.  First, Papias presented the teaching of "a certain millennium after the resurrection, and that there would be a corporeal reign of Christ on this very if they were authorized by the apostolic narrations..."  That is to say that Papias affirmed that the apostles taught that this was so.  Papias spent many years learning from John and others of the earliest leaders of the Church.  Eusebius gives no support for his assertion that Papias, who was universally acknowledged and praised as faithful to the apostolic teaching, "imagined" such substantial departures from the teaching of the apostles.
Second, although Eusebius elsewhere praises Papias for his virtue and learning, here he demeans him as deceived and dull.  The only "evidence" that Eusebius has for this derogatory characterization is that Papias believed in a millennial reign of Messiah on the earth.  In contradiction to his praises elsewhere, Eusebius demeans Papias here because he wants to undermine such belief.
There is ample evidence in support of the great spiritual understanding of Papias.  Among other faithful endeavors which he performed, Papias is credited with having written the Gospel of John at the dictation of the Apostle.  The Gospel of John is certainly not an un-spiritual document.
Third, Eusebius admits that "most of the ecclesiastical writers, urging the antiquity of the man, were carried away by a similar opinion."   Therefore, according to Eusebius, most of the ecclesiastical writers believed "that there would be a corporeal reign of Christ on this very earth."  Eusebius asserts, without any supporting evidence, that the only reason they believed it was "the antiquity" of Papias.    During the time of Papias, and before, there were some who held to a variety of different doctrinal errors.  "Most of the ecclesiastical writers" were not
lead astray by the "antiquity" of these false teachers.  Nor were they lead astray by the antiquity of Papias.  It was not in Papias' antiquity alone that these believers trusted.  Papias lived a consistent life of proven service to the Lord, His apostles, and His Church.  That is why most of the ecclesiastical writers trusted his transmission of the apostolic teaching.  Eusebius did also, except in this one instance.
Eusebius' opposition to this apostolic teaching was so great, that he certainly would have, if he could have, presented the teaching of anyone contemporary with the apostles or their disciples who believed in the "mystical," spiritual interpretation which he himself adopted.  However, he is not able to present the writings of anyone - not one - from that earlier age who believed as he did.  He had the documents.  He had the full support of the Emperor Constantine.  But he still could not produce any evidence in support of his position.   That being the case, Eusebius chose not to present the millennial teaching of "most of the ecclesiastical writers," because it contradicted his own beliefs.  In fact, he does not quote from any of them on this matter.  Their writings were known and still in circulation in the early fourth century when Eusebius wrote his Ecclesiastical History. 
Jerome, who wrote at about the end of the fourth century, said, "This
(Papias) is said to have promulgated the Jewish tradition of a Millennium,
and he is followed by Irenaeus, Apollinarius and the others who say that
after the resurrection the Lord will reign in the flesh with the saints." 5
 Irenaeus and Apollinarius are also described by Eusebius as learned,
virtuous, faithful witnesses of the apostolic faith.
Eusebius says, "About this time also, the beloved disciple of Jesus, John the
apostle and evangelist, still surviving, governed the churches in Asia, after
his return from exile on the island, and the death of Domitian.  But that he
was still living until this time, it may suffice to prove, by the testimony
of two witnesses.  These, as maintaining sound doctrine in the church, may
surely be regarded as worthy of all credit: and such were Irenaeus and
Clement of Alexandria.  Of these, the former, in the second book against
heresies..." 6
  According to Eusebius, Irenaeus maintained sound doctrine in the church.
   He wrote against heresies.  He was a faithful and true witness.  Irenaeus
believed that the Lord would reign in the flesh on earth with the saints.
Jerome, since he also rejected "the Jewish tradition of a Millennium," did
not quote from "the others."  He rejected the writings of the "most," or all,
of the early Church that believed in it.  Their writings were still available
when he wrote.  As with Eusebius, Jerome was also unable to offer evidence to
the contrary from other early Church writers.
Eusebius, Jerome, and others had these writings available to them, but they
did not want to make them known.  These writings of "most of the
ecclesiastical writers" who promulgated "the Jewish tradition of a
Millennium" are not available to us today.  That is not, however, evidence
that the Church never believed as they did.  It is only evidence that some
later in the Church did not care to preserve these writings.
Part of one of those early writings that has survived, "The Revelation of
Peter," clearly speaks of a restoration of Israel.  In a portion parallel to
Matthew 24, Mark 13, and Luke 21, Jesus is seated on the Mount of Olives, and
the disciples come to him asking, "Make known unto us what are the signs of
thy Parousia [appearing] and of the end of the world..." 7 As Jesus tells
them the signs, He admonishes them, "And ye, receive ye the parable of the
fig-tree thereon: as soon as its shoots have gone forth and its boughs have
sprouted, the end of the world will come." 8
Peter then asks Jesus to explain the parable of the fig tree that signals the
end of the age and the coming of the Lord. (cf. Mt.24:32-36; Mk.13:28-32;
Lk.21:29-33)  Jesus replies, "Do you not understand that the fig tree is the
house of Israel?  Truly, I tell you, when its branches have sprouted at the
end of the world, false Christs shall arise.  They will arouse expectation
and say, 'I am the Christ who once came into the world.'  But this liar is
not the Christ.  When they reject him, he will murder with the sword.  Then
shall the branches of the fig tree, which is the house of Israel, shoot
forth.  There shall be many martyrs by his hand...." 9
"The Revelation of Peter,"  a short work which does not speak of much more
than the restoration of Israel, was not considered an heretical document, far
from it.  The "Muratorian Canon," written about 180 A.D., lists the writings
which the Church (or part of it) then acknowledged as canonical.  It
mentions, "...We also accept a Revelation by John and one by Peter, although
some of us do not want the latter to be read aloud in the Church." 10
"The Revelation of Peter" was considered part of the canon.  It was accepted
as the Word of God.  Yet some in the Church did not want it to be read to the
people.  Certainly that is unusual.  (Eusebius was familiar with "The
Revelation of Peter," but he did not quote from it.)
Those in the Church who did not want "The Revelation of Peter" to be publicly
read were not arguing that it was not the Word of God.  It simply contained
material that they did not like.  Even if they thought it was the Word of
God, they did not want it to be read to the Church.  Though today we do not
consider it canonical, it still is firm documentary evidence of what the
early Church believed.
Justin's Dialogue with Trypho the Jew, dated about 160 A.D., also offers
evidence of what the early Church believed.  It is interesting as a seemingly
transitional work.   The dialogue apparently took place shortly after the Bar
Kokhba Rebellion of 132-135 A.D., but was not written down for at least
twenty years.
Justin points to the desolation of Israel and says to Trypho, "And therefore
all this has happened to you rightly and well.  For ye slew the Just One and
His prophets before Him, and now ye reject, and, as far as in you lies,
dishonour those that set their hope on Him, and God Almighty and Maker of the
universe who sent Him, cursing in your synagogues them that believe on
Christ.  For you have not authority to raise your own hands against us,
because of them who are now supreme.  But as often as you could, this also ye
did." 11
 Justin believed that the Church was the true Israel, but not in the
replacement sense later adopted.  "For we are the true and spiritual
Israelitish nation, and the race of Judah and of Jacob and Isaac and Abraham,
who when he was still uncircumcised received witness from God for his faith,
and was blessed, and was called father of many nations - we, I say, are all
this, who were brought nigh to God by Him who was crucified, even Christ..."
"As therefore from that one Jacob, who was also surnamed Israel, your whole
nation was addressed as Jacob and Israel, so also we who keep the
commmandments of Christ, are, by virtue of Christ who begat us unto God, both
called and in fact are, Jacob and Israel and Judah and Joseph and David, and
true children of God."13
Justin maintains that Gentiles "who keep the commandments of  Christ, are, by
virtue of Christ" also full members of Israel.  He does not seem to believe
that the Church has replaced the Jews,  but rather that Gentile Christians
have been grafted into Israel through Jesus.  "When therefore God blesses,
and calls this people Israel, and cries aloud that it is His inheritance, how
is it that you do not repent, both for deceiving yourselves as though you
alone were Israel, and for cursing the people that is blessed of God?" 14
"Trypho said: Do you indeed intend to say that none of us shall inherit
anything in the holy mountain of God?
"And I replied: I do not mean that.  But they who persecuted Christ, and
still persecute Him, and do not repent, shall not inherit anything in the
holy mountain.  While the nations [Gentiles] that have believed on Him, and
have repented for all the sins they have committed - they shall inherit, with
all the patriarchs and the prophets and the righteous men that have been born
of Israel." 15
According to Justin, it is not Jews only who are now Israel, but also
Gentiles who believe in Jesus.  For Justin, because the Gentiles who believe
in Jesus are now part of Israel, they also, along with the righteous Jews,
will inherit what God has promised Israel.
 As for the nature of that inheritance, Trypho pointedly asks, " 'do you
acknowledge of a truth that this place Jerusalem will be rebuilt, and expect
that your people will be gathered together and rejoice with Christ, together
with the patriarchs and the prophets, and the saints of our race, or even of
them who became proselytes, before your Christ came...?'
"[Justin replies,] 'I have acknowledged to you earlier that I and many others
do hold this opinion, even as you also know well that this is to take place.
 But I also informed you that even many Christians of pure and godly mind do
not accept it.  For I made it clear to you that those who are Christians in
name, but in reality are godless and impious heretics, teach in all respects
what is blasphemous and godless and foolish....For it is not men, or the
doctrines of men, that I choose to follow, but God and the doctrines that
come from Him.
"For even if you yourselves have ever met with some so-called Christians, who
yet do not acknowledge this, but even dare to blaspheme the God of Abraham,
and the God of Isaac, and the God of Jacob...  But I, and all other entirely
orthodox Christians, know that there will be a resurrection of the flesh, and
also a thousand years in a Jerusalem built up and adorned and enlarged, as
the prophets Ezekiel and Isaiah, and all the rest,  acknowledge.'"16
"And, further, a man among us named John, one of the apostles of Christ,
prophesied in a Revelation made to him that they who have believed our Christ
will spend a thousand years in Jerusalem, and that afterwards the universal,
and, in one word, eternal resurrection of all at once, will take place, and
also the judgment." 17
For Justin, "all entirely orthodox Christians" believed that Jesus would
reign on the earth for a thousand years in a glorified Jerusalem.  Those
"so-called Christians who yet do not acknowledge reality are
godless and impious heretics" who "dare to blaspheme the God of Abraham, and
the God of Isaac, and the God of Jacob."
Eusebius knew Justin's Dialogue with Trypho.  He quotes from it, praising
Justin as "a true lover of sound philosophy."  He characterizes Justin as
courageous, a man "of cool deliberation and judgment." 18
But when it comes to Justin's declaration that those who do not acknowledge
the future coming and reign of the Lord on the earth from Jerusalem are
"godless and impious heretics," Eusebius ignores Justin.  He neither  quotes,
nor mentions, nor comments.  He cannot pretend that Justin was lead astray by
Papias, so he simply pretends that Justin never said what he said.  For
Eusebius, it is not part of the history of the Church, because it is not what
he wants the Church to believe.
1. E. Ferguson, "The Terminology of Kingdom in the Second Century," in Studia
Patristica, Vol.XVII, P.670, edited by Elizabeth A. Livingstone, Pergamon
Press, Oxford, 1982
2. ibid., P.673
3. The Ecclesiastical History of Eusebius Pamphilus, translated by Christian
Frederick Cruse, op. cit., Bk.3, Ch.36, P.120
4. ibid., Bk.3, Ch.39, P.126
5. J.B. Lightfoot and J.R. Harmer, editors, The Apostolic Fathers, Baker Book
House,  Grand Rapids, MI, 1988, P.532 (de vir. illust. 18)
6.  The Ecclesiastical History of Eusebius Pamphilus, Bk.3, Ch.23, P.104-105
7. Edgar Hennecke, The New Testament Apocrypha, Vol. 2, edited by Wilhelm
Schneemelcher, translated by R. McL. Wilson, The Westminster Press, Phila.,
1965, P.668  For the full text of this section, chapter 2, in the Ethiopic
text, see Pp.668-669
8.  ibid., P.668
9. Eberhard Arnold, The Early Christians after the Death of the Apostles,
Plough Press, Farmington, PA., 1972, P.295
10. ibid., P.167
11. Justin Martyr, The Dialogue with Trypho, translated by A. Lukyn Williams,
S.P.C.K., London, 1930, Pp.33-34, Sec. 16.4
12. ibid., P.24, Sec. 11.5
13. ibid., Pp.256-257, Sec. 123.7-9
14. ibid., P.255, Sec. 123.6
15. ibid., P.52, Sec. 25.6-26.1
16. ibid., P.169, Sec. 80.1-5
17. ibid., P.172, Sec. 81.4
18. The Ecclesiastical History of Eusebius Pamphilus, Bk.4, Ch.8, Pp.135-136