Revelation 9:13

At the sounding of the sixth trumpet, are said to be loosed the four angels bound in the river Euphrates. By these four angels, and the two hundred millions of horsemen, many understand the devils and their instruments, men incited by them in antichrist's time, to make war and persecute the Church of Christ, who shall destroy a third part, that is, a great part of men then in the world. Divers others apply this to the Persians, the successors of the Parthians, who about the middle of the third age [century], in the time of Valerian, a great persecutor of the Christians, passed the Euphrates, which used to be the bounds of the Roman empire to the east, defeated, took, and kept Valerian prisoner, which by its consequences gave a great stroke to the Roman empire. See the bishop of Meaux, Pere Alleman, &c. (Witham)