Just the other night I was rereading Dr. Wess Roberts' book Leadership Secrets of Attila the Hun, which was published in 1989, and which makes for interesting reading in these times, such as where Attila links authority with responsibility, or remarks that the first goal for every Hun chieftain is the good of the nation.
It is a historical fact that Attila was all set to invade and sack Rome about AD 452, and was met one-to-one by Pope Leo I. What was said between them is lost to history, but Attila did turn back.
The punch line is the one leadership rule Dr. Roberts didn't make explicit:
When the Pope talks, obey him!