Since the start of Christianity, there have been over 260 popes serving. Sometimes, Popes ruled kingdoms and declared wars, if Vatican City was in the empire. The Pope the declared the Crusades on the Muslims was Pope Urban II. He declared so many until they got their land back.
The first Pope was of course Saint Peter and there were altogether 265 Popes after him, and the current is Pope Francis I.
Urban II declared Crusades in 1095 after the council in Clermont in 1095. The Crusades started after Byzantine emperor asked for help in the fight against the Seljuk Turks, but became something totally different that he expected.
