Revelation 9:13 And the sixth angel sounded, and I heard a voice from the four horns of the golden altar which is before God,
14 Saying to the sixth angel which… had the trumpet, Loose the four angels which are bound in the great river Euphrates.
15 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.
Now the second WOE as the sixth angle sounded. The horns mean power and the golden alter is where God is. This trumpet was to release the four angles from the four corners of the earth which means it will be world wide with its destruction. They were prepared for 1year 1 month 1 day and 1 hour to slay another third of the people who have not accepted Christ. It is estimated that 1 and 1/2 billion people will die in this woe.