The new pope said he would be guided by a key document that his predecessor wrote listing the church’s priorities, including a “loving care for the least and the rejected.”

ROME — The new Chicago-raised Pope Leo XIV faces an immediate challenge in his native country: taming the brawling U.S. tribe of Catholics, riven by political divisions that have thwarted the will of his predecessors.

Pope Leo I tangled with Attila the Hun and won. Pope Leo III crowned Charlemagne as the first Holy Roman Emperor. This is the history of a legendary papal namesake.