May I suggest that you read ‘Thirteen Lectures on the Apocalypse’ by Robert Roberts.
See here: http://www.antipas.org/books/13_lectures/lecture4.html
THE SIXTH SEAL.
The sixth seal shows us a different state of things altogether. It introduces us to something that we may look upon as in the nature of a retribution for the evil deeds performed under the fifth seal.
"And I beheld when he had opened the sixth seal, and lo, there was a great earthquake; and the sun became black as sackcloth of hair, and the moon became as blood; and the stars of heaven fell unto the earth, even as a fig tree casteth her untimely figs when she is shaken of a mighty wind. And the heaven departed as a scroll when it is rolled together; and every mountain and island were moved out of their places. And the kings of the earth, and the great men, and the rich men, and the chief captains, and the mighty men, and every bondman, and every free man, hid themselves in the dens and in the rocks of the mountains; and said to the mountains and rocks, Fall on us, and hide us from the face of him that sitteth on the throne, and from the wrath of the Lamb: for the great day of his wrath is come; and who shall be able to stand?" (6:12-17).
What is there in Roman history, succeeding to the reign of Diocletian, at all corresponding to this symbolic picture of a universe in tempestuous dissolution? Looking at the political universe which was the subject of the symbol, we have not to go far to see. Following close on the fearful persecutions of the fifth seal, we behold the Pagan world in a state of violent and revolutionary turmoil ending in the overthrow of Paganism, and of the entire system established on the basis of the national idolatry, the old order of things in Rome (a thousand years old) upset, and a new order of things established. The son of one of Diocletian's colleagues was the instrument of this momentous revolution. His name is of world-wide renown. Constantine, the son of Constantius, who ruled the west, was brought up with a bias in favour of the Christians, inherited from his father. His father very much disapproved of the persecutions ordered by Galerius and Diocletian, and successfully used his authority in shielding the Christians from the extreme measures dealt out to them in other parts of the empire. His son Constantine early took their part, and perceiving them a growing party in the State, proclaimed himself their protector. On the death of his father he was proclaimed His successor by the army of the West, to the dismay of the reigning emperors in Italy and the east, who were supporters of the Paganism of the State, and who viewed with alarm the elevation of a man of known capacity who had proclaimed sympathy with the Christians. The difference of feeling between them soon led to war, and this was ended in the ruin of Paganism. Constantine exhibited a celerity and skill in his movements which baffled and overpowered his enemies. He marched to Italy and was over the Alps before almost the of his intentions had reached the Imperial Court in Rome. Every battle was for him a victory, and in a short time he found himself in Rome the unchallenged ruler of the principal part of the empire. This was a great change for the Christians, who were emancipated from all their disabilities and received into imperial favour. After a short peace with his colleagues of Illyricum and the East, the war was renewed. It was felt by all that the issue was between Paganism and Christianity. The two elements had long been fermenting one with the other throughout the State, and the hour had come to decide which was to have the ascendancy. The question was effectually decided by the extraordinary success uniformly attending the arms of Constantine. The armies of the Pagan emperors were completely defeated; and Constantine, the befriender of the persecuted Christians, became sole master of the empire. The constitution of the world was completely changed. The earth had been the subject of a great quake, lasting for years and resulting in all the effects portrayed in the symbolism; the sun of the political universe -- the Pagan emperorship (both high-priest and defender of Paganism) had become darkened or eclipsed; the moon, or ecclesiastical element of the Roman polity -- the Pagan clergy -- the priests of the gods -- shining by the borrowed light of the throne, even as the moon by the light of the sun -- disappeared in blood; the stars of the political firmament, the numerous magnates of various kinds and degrees exercising authority in the empire, by the goodwill of the emperor, fell out of their places with the overthrow of their master, to give place to Christian successors. The heaven or whole sphere of established imperial authority, was rolled up and put aside as a thing of the past the various mountain and island kingdoms and principalities subsisting under Rome, moved out of their places, and all orders and ranks of Roman society, having participated in the persecution of the Christians, recognized in the public calamities occurrent, the retribution inflicted by "the God of the Christians", and were panic stricken to the extent of desiring concealment, even in death, from the terrors that swept through the length and breadth of the Roman Empire. One of the Pagan emperors of the time, dying in torments, protested in his agony that he had not been guilty of persecution of the Christians. It is to be gathered from the writings of the age that all recognized the Constantinian revolution as a retribution from the God of the Christians, which it doubtless was.
This change was one which affected the entire civilized world. Rome wielded universal empire over the civilized races of men, so that what affected Rome affected all the earth, and a change so radical, effected so violently, could not better be represented than by the symbolism of the sixth seal. It was a change that took considerable time to accomplish. It was not the work of one year. It occupied several years. When accomplished, it wrought a wonderful change in the position of the friends of Christ. From being proscribed and hated and hunted down and destroyed, they became the favourites of the authorities, upon whom were lavished the revenues and the favours formerly bestowed on the Pagan priesthood. Such a change naturally gave enlarged scope for their development and consolidation. This appears to have been one of the providential purposes served by the overthrow of the Pagan adversary, as we may gather from the symbolism immediately succeeding the sixth seal....
I hope you find this helpful.