Daniel's prophecy about the Fourth World Empire, thus refers to that of Ancient Rome. That empire would last for many centuries — commencing at the final demise of the Third World Empire of Hellenism, especially when in B.C. 32 Egypt as the last phase of the Ptolemaic Hellenic Empire was annexed by Rome after the Battle of Actium (cf. Daniel 11:42f).
All of the Pre-Reformers and Protestant Reformers — without exception — agree on this. See: Wycliffe; Brute; Luther; Oecolampadius; Melanchthon; and Latimer. Cf. too Puritans like: Downham; Brighton; Mede; Parker; Poole; and Davenport — as well as Increase Mather; Jurieu; Cocceius; Cotton Mather; Matthew Henry; Sir Isaac Newton; Jonathan Edwards; Willison; Bishop Thomas Newton; Faber; Dr. Thomas Scott; Horne; Keith; James H. Begg; Bishop Daniel Wilson; Bickersteth; Albert Barnes; Pusey; Fairbairn; Leupold; Carroll; Edward J. Young; Rushdoony; and many others.
Even that great secular historian of Rome, Gibbon himself, wrote:1755 "The arms of the republic" of Rome, "always victorious in war — advanced with rapid steps to the Euphrates, the Danube, the Rhine, and the [Atlantic] Ocean…. Images of gold or silver or brass that might serve nations and their kings, were successfully broken by the 'iron monarchy' of Rome. See Daniel 2:31-40" — cf. 2:34 & 2:41-43 & 7:23f.
The 1560 Geneva Bible of John Knox and Mrs. John Calvin's brother-in-law Rev. Dr. William Whittingham, has a crisp comment on all of this. It points out: "By gold, silver, brass and iron are meant the Chaldean, Persian, Macedonian and Roman kingdoms which would successively rule all the World — till Christ (Who is here called 'the Stone') Himself come and destroy the last."
Also John Calvin himself, in his 1561 Commentary on Daniel (2:44f), summarizes it very admirably. For he insisted: "There is no doubt, then, that Daniel intended the Romans by the fourth empire."
We have seen that the four successive World-kingdoms were represented by a composite statue of a man with a golden head, silver arms, brass thighs, and iron legs (with feet of iron and clay).1754 But the fourth kingdom of Rome would be particularly conglomerate — with no real internal consistency. Indeed, the Roman Empire was truly just like an ultimately-brittle mixture of iron and clay.1754
Predictably, the "legs" of that Roman Empire, broken in principle by the incarnation and resurrection and ascension of Jesus Christ, themselves later re-divided into ten different "toes" or regional provinces throughout Europe. Thus: Irenaeus; Tertullian; Hippolytus; Eusebius; Sulpicius Severus; Jerome; Andreas; Jephet ibn Ali; Abraham ben Ezra; Luther; Melanchthon; and also many other subsequent authorities (including Edward Gibbon).1755
Stated Gibbon: "The warlike Barbarians…subverted the Empire and embraced the Religion of the Romans. The Goths were the foremost of these savage proselytes…. The Ostrogoths, the Burgundians, the Suevi and the Vandals [and others] listened to the eloquence of the Latin clergy…. The decay of Rome…has already shown that the powers of government were divided."1755
Previously, Ancient Rome had divided and ruled her subjects. But the Lord Christ would now divide and rule — Rome!
This began to occur "in the fullness of time."1756 For it was then that the Son of God, our Lord and King Jesus, started destroying the remains of all
the World-kingdoms of ancient times. He came down from Heaven to Earth, in the days of the heathen Roman hegemony. It was then that He and His Messianic "Stone Kingdom" rolled down, like a huge Rock, from the Mountain of God — and cracked the composite statue, after colliding with it.1757