From the martyrology:
"St. John Capistrano, confessor, a priest of the Order of Friars Minor, who is mentioned on the 23rd of October."
St John Capistrano (1386-1456) was an Italian Franciscan Friar who was famous as a preacher, theologian, and inquisitor. At the age of 70 he led a crusade against the invading Ottoman Empire, successfully raising the siege of Belgrade along with the Hungarian military commander John Hunyadi, even leading his own contingent into battle.
St John is one of those saints who if he lived today would surely be a blogger: when he was not preaching, he employed himself in writing tracts against heresy of every kind. He also assisted St Bernardine of Siena in the reform of the Franciscan Order.
He died of the plague in the wake of the battle against the Ottomans.