There is a story on americancatholic.org that shows God working through Sylvester:
Once in a city where civil war was raging, Sylvester was commanded by Francis to drive the devils out. At the city gate Sylvester cried out: "In the name of almighty God and by virtue of the command of his servant Francis, depart from here, all you evil spirits." The devils departed and peace returned to the city.
Praise God for such men who inspire us to want to be better.