Charlie Brown and Franz Stigler shared a skill: they were both pilots trained in warfare.
World War II made them enemies, and an incident in December 1943 brought them physically close.
Stigler had the upper hand, and could have shot Brown's plane out of the sky.
But he didn't, and the story of his decision and its aftermath is told by journalist/historian Adam Makos in his book A Higher Call: An Incredible True Story of Combat and Chivalry in the War-Torn Skies of World War II.