Then the sixth angel sounded: And I heard a voice from the four horns of the golden altar which is before God, saying to the sixth angel who had the trumpet, “Release the four angels who are bound at the great river Euphrates.” So the four angels, who had been prepared for the hour and day and month and year, were released to kill a third of mankind. Now the number of the army of the horsemen was two hundred million; I heard the number of them. And thus I saw the horses in the vision: those who sat on them had breastplates of fiery red, hyacinth blue, and sulfur yellow; and the heads of the horses were like the heads of lions; and out of their mouths came fire, smoke, and brimstone. (Rev 9:13-17 NKJ)
The fifth angel sounded the trumpet, and the angel that had fallen (Satan) was given the key to open the abyss. When that door was opened, all manner of things can happen and as far as the Roman Empire was concerned, did happen. If fact there were six reasons why the Roman Empire became weak.
1. Invasion by the Barbarians
2. Economic woes and an over-reliance on slave labor
3. A divided empire
A weakening of an empire such as Rome, code name ‘Babylon’ by John was destined to fall. Sixth trumpet blows and the angels that had been bound were released. Powers and principalities that had been waiting in the east came marching in, and the downfall of Rome was inevitable.
When God is removed, and Satan is given authority, the domino effect, be it personal, national or international is disastrous.