Lewis, Anthony R. "…But the Sword!"
Divergence: 1202 CE
What if: Francis Bernardone of Assisi became a Crusader rather than a priest, but quit in disgust after witnessing the sack of Constantinople.
Summary: Francis is drafted by the pope to lead a new militant order and leads the crusade that recaptures Jerusalem in 1221, causing his later canonization.
Published: In Alternate Warriors (ed. Mike Resnick), q.v.