What does Revelation 9:16 mean?

This passage has been describing four imprisoned angels—demons—released to kill one third of the remaining human population. Here, however, John suddenly refers to a numbered army. Some speculate that the horde of demonic locusts, released earlier in the chapter (Revelation 9:3) might be involved in controlling or guiding this army along with the four released angels.

This verse gives the number of the invading cavalrymen as "twice ten thousand times ten thousand," which is a staggering two hundred million! John makes a point of saying that he heard this figure. Rather than giving a generic figure, or some number he might have been able to count, John relays what he was told about the size of this army. That implies the count is meant to be taken literally.

Isaiah 8:7–8 depicts this invasion as the work of the king of Assyria. The future leader of the invasion is referred to in Ezekiel 38:1–3, using the infamous phrase "Gog and Magog," or "Gog, of the land of Magog." Ezekiel describes the army commanded by "the chief prince of Meshech" as "horses and horsemen, all of them clothed in full armor, a great host, all of them with buckler and shield, wielding swords" (Ezekiel 38:4). The northern invader will seek Israel's resources (Ezekiel 38:10–13). Like a flood, this army will sweep over Israel and reach Jerusalem's neck (Isaiah 8:8).

In John's era, it would have been unthinkable to imagine an army so enormous—according to some historians, the entire world population was less than two hundred million in AD 95. In the modern era, of course, there are nations such as India and China with total populations five times that size. As a result, many equate this army of two hundred million horsemen with an army from the Orient, described in Revelation 16. However, that attack occurs when the sixth bowl is poured out. It seems the judgments follow a roughly chronological order: first the seal judgments, then the trumpet judgments, and finally the bowl judgments.