sentences:  Political weakness compelled the Renaissance Papacy to adopt an acquiescent and unchallenging position when approached for requests for privileges in favour of these ventures.Without a navy of his own to police the islands, the Pope opted in favor of the Portuguese as the lesser of two evils.In 1476 Pope Sixtus IV reiterated the concerns expressed in "Sicut dudum" in his papal bull, "Regimini gregis", in which he threatened to excommunicate all captains or pirates who enslaved Christians.