Military Orders
Origin of the Hospitallers
The Hospitallers had a somewhat more traditional origin. They began as a group of merchants from Amalfi who banded together to live as monks and to serve the pilgrims to Jerusalem. They actually formed in the 1080s, prior to the First Crusade. They soon had daughter houses back in Italy (Amalfi is in Italy), along the pilgrimage route. Pope Paschal II recognized it as a monastic Order in 1113.
In these early years, the Hospitallers did not fight, but were dedicated to helping the pilgrims, especially to providing the services of a medieval hospital: food, shelter, and a basic sort of protection, at least for the night. They had no military function at all.
The foremost duty of the Hospitallers was the care of the poor and the sick, and this order never lost sight of that purpose. Even when the Order was heavily engaged in military activities, care of the poor was a major concerns. At its height, the Hospital of St. John of Jerusalem could care for two thousand people.
The Hospitallers nevertheless acquired military duties from early in their history. It's not at all clear how this happened; perhaps the Order was joined by a large number of knights, perhaps it was the influence of only a few. In any case, we do know that in 1136, King Fulk gave into their care the castle at Beth Gibelin. It's possible that at first the castle was garrisoned with mercenaries, but by the middle of the century, the Hospitallers had acquired other castles that had to have been garrisoned by brothers of the order: Krac des Chevaliers in 1144 (probably the most famous of all crusader castles), Belvoir in 1168, Marqab in 1186.
From the middle of the 12th century on, the Hospitallers were one of the most important military forces in the Kingdom of Jerusalem.