And the amiss which were in heaven followed him upon white horses, clothed in fine linen, white and clean; which are … white, pure. These armies are not merely the angels, but the "called, chosen, and faithful" of Revelation 17:14, "the bride" of Revelation 17:8, who are described as being arrayed in white in Revelation 6:11, and Revelation 6:8 of this chapter.
Those commentators who consider that the angels only are intended, and not the saints, forget the double nature of the vision; it is not only a description of Judgment meted out, but also of a war waged.
(On "white" and "fine linen," see previous chapters.