The Order of Saint Lazarus of Jerusalem, also known as the Leper Brothers of Jerusalem or simply as Lazarists, was a Catholic military order founded by crusaders around 1119 at a leper hospital in Jerusalem, Kingdom of Jerusalem, whose care became its original purpose, named after their patron saint, Lazarus. It was recognised by King Fulk of Jerusalem in 1142 and canonically recognised as a hospitaller and military order of chivalry under the rule of Saint Augustine in the Papal bull Cum a Nobis Petitur of Pope Alexander IV in 1255. Although they were centered on their charism of caring for those afflicted with leprosy, the knights of the Order of Saint Lazarus notably fought in the Battle of La Forbie in 1244 and in the Defense of Acre in 1291. The titular seat was successively situated at Jerusalem, Saint-Jean-d'Acre and - after the fall of the Kingdom of Jerusalem - split in two main branches in Italy and in Château Royal de Boigny-sur-Bionne in France.