Adam Clarke on Revelation 17:13

These have one mind, and shall give their power and strength unto the beast - Therefore the ten horns must constitute the principal strength of the Latin empire; that is to say, this empire is to be composed of the dominions of ten monarchs independent of each other in every other sense except in their implicit obedience to the Latin Church. The beast in this and the preceding verse is distinguished from its horns, as the Whole Latin empire is distinguished in history from its constituent powers. See on Rev 17:16 (note).