Rev 9:13-21
And 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 which had the trumpet, Loose the four angels which are bound in the great river Euphrates. And the four angels were loosed, which were prepared for an hour, and a day, and a month, and a year, for to slay the third part of men.
The four horns of the golden altar before God in His tabernacle on earth use to be sprinkled with blood from the animal sacrifice to cleanse and purify it from the sins of the Israelite's, Leviticus 4:7, 16:18. The golden altar being in the tabernacle of God before His throne in heaven is that of the four gospels of grace. The voice coming out of the four horns is Jesus who is the only one worthy of opening the seven seals and sending out the seven angels with a trumpet sound which means one sent out by Gods great power and authority.
Jesus now speaks to the angel with the sixth trumpet and commands him to let loose the four angels that are bound in the Euphrates River that have been prepared by God for the hour, day, month and year of His angry indignation against those who follow after other gods. The four angels are Gods warring angels who will war against the enemies of God killing a third of mankind that refuse to repent.
And the number of the army of the horsemen were two hundred thousand thousand: and I heard the number of them. And thus I saw the horses in the vision, and them that sat on them, having breastplates of fire, and of jacinth, and brimstone: and the heads of the horses were as the heads of lions; and out of their mouths issued fire and smoke and brimstone. By these three was the third part of men killed, by the fire, and by the smoke, and by the brimstone, which issued out of their mouths. For their power is in their mouth, and in their tails: for their tails were like unto serpents, and had heads, and with them they do hurt.
John knows the number of the horsemen as he heard the number to be two hundred million. The four angels will take each to them five hundred thousand horsemen or Gods warring angels and since there are four angels that lead this army I would think they would go out to the four corners of the earth as they kill a third of the earths population.
Each horseman has a breastplate of fire, jacinth and brimstone. The breastplate represents the heart of these two hundred million warring angels that are being lead by the four angels as they are all subject to Gods will and purpose. The horse’s heads being likened unto a lions head represents strength, predatory and majesty of a ruler or king as being God in His fierce power of this particular chastisement on men. The fire, smoke and brimstone literally proceeds out of the mouths of these warring angels as we read in the literal fire of God in Exodus 9:23; 2 Kings 1:10; Numbers 11:1; 16:35; Leviticus 21:9; Psalms 104:4. By these three that are fire, smoke and brimstone a third of mankind will be killed.
For their power is in their mouth, and in their tails: for their tails were like unto serpents, and had heads, and with them they do hurt. And the rest of the men which were not killed by these plagues yet repented not of the works of their hands, that they should not worship devils, and idols of gold, and silver, and brass, and stone, and of wood: which neither can see, nor hear, nor walk: Neither repented they of their murders, nor of their sorceries, nor of their fornication, nor of their thefts.
Here is the importance of the area of the Euphrates River and what the four angels were prepared for to battle against. Surrounding the Euphrates River are four Assyrian Babylonian type countries that make up one third of the worlds population. These countries are Syria, Turkey, Iran and Iraq (Babylon) that make up parts of the old Assyrian nations.
Assur, son of Shem and Grandson of Noah, defiled himself against God and was made god over the Assyrian nations he founded as the Assyrians called him Asnapper and set up monuments to worship him and named their capitol after Assur, Ezra 4:10, Nahum 3:1-19. You will need to do a more extended study in who Assur was and how these four nations came to be as it would be to lengthy to add to this particular study in Revelations.
The power was in their (Assur) mouth from the beginning as Noah and his sons were faithful to God teaching their families through the power and authority of Gods spoken word in all truths. From the time of Assur falling away from God unto even present day the power is in their (Assyrian/Babylonian type nations) tail as their prophets teach lies, Isaiah 9:12-16, leading the people of these nations to fall prey to worship devils and set up their various idols that are made by hand that are abominations to God. This is similar to the judgment of Ephraim in Isaiah 9:8-21 and the destruction of Assyria in Isaiah 10:1-19.
These two hundred million warring angels that are lead east, west, north and south through these four nations by the four angels who have been prepared will literally strike down one third of the world’s population. God only needs to speak those things into existence as the warring angels breathe real fire out of their mouths as we read in other scriptures to this fact to consume those who refuse to repent.
This comes out to be two hundred million of a seven billion population that is in the world today that will be killed by these warring angels. These four nations refuse to repent of their murders, sorceries, fornication and thefts against God and his faithful servants that have been martyred and will continue to die a martyr’s death for the sake of the witness and testimony of Jesus they carry through out these nations.