Barons' Crusade
The Barons' Crusade, also called the Crusade of 1239, was in territorial terms the most successful crusade since the First Crusade. Called by Pope Gregory IX, the Barons' Crusade broadly spanned from 1234-1241 and embodied the highest point of papal endeavor "to make crusading a universal Christian undertaking." Gregory called for a crusade in France, England, and Hungary with different degrees of success. Although the crusaders did not achieve any glorious military victories, they used diplomacy to successfully play the two warring factions of the Muslim Ayyubid dynasty (As-Salih Ismail in Damascus and As-Salih Ayyub in Egypt) against one another for even more concessions than Frederick II gained during the more well-known Sixth Crusade. For a few years, the Barons' Crusade returned the Kingdom of Jerusalem to its largest size since 1187.