Revelation 9:14
It spoke to the sixth angel--the angel with the trumpet--and said 'Let loose the four angels that are in chains at the great river Euphrates.'
Revelation 16:12
Then the sixth angel emptied his bowl upon the great river Euphrates; and the water in the river was dried up, so that the road for the Kings of the East might be made ready.
Revelation 7:1
After this, I saw four angels standing 'upon the four corners of the earth,' restraining the four winds of the earth, that no wind should blow over the earth, or over the sea, or against any tree.
Revelation 8:2
Then I saw the seven angels who stand before God, and seven trumpets were given to them.
Revelation 8:6
Then the seven angels holding the seven trumpets prepared to blow their blasts.
Revelation 9:15
Then the four angels, that were held in readiness for that hour and day and month and year, were let loose, to destroy a third of mankind.