A.T. Robertson Commentary Revelation 19:18

"that ye may eat the flesh of kings, and the flesh of captains, and the flesh of mighty men, and the flesh of horses and of them that sit thereon, and the flesh of all men, both free and bond, and small and great." — Revelation 19:18 (ASV)

That ye may eat (ινα φαγητε). Purpose clause with ινα and the second aorist active subjunctive of εσθιω.

The flesh of kings (σαρκας βασιλεων). "Pieces of flesh" (plural of σαρξ, flesh) and of all classes and conditions of men who fell in the battle (6:18; 11:13; 13:16; 19:5; 20:12). War is no respecter of persons.