That these Four Angels who were bound at the river Euphrates, were bad angels is seen from the fact that they were bound, and that they are the leaders or commanders of an army of 200,000,000.
This army of horsemen is a supernatural army. It is not made up of ordinary men and horses.
The fact that these angels were bound at the Euphrates, where Satan's seat was in years past, and where it is to be again in the City of Babylon restored, and from where he will do his evil work, makes it clear that this army is a part of Satan's forces.