It was founded in the crusader Kingdom of Jerusalem in the 12th century and had headquarters there until , thereafter being based in Kolossi Castle in Cyprus β , the island of Rhodes β , Malta β , and Saint Petersburg β The Hospitallers arose in the early 12th century at the height of the Cluniac movement , a reformist movement within the Benedictine monastic order that sought to strengthen religious devotion and charity for the poor.
Earlier in the 11th century, merchants from Amalfi founded a hospital in Jerusalem dedicated to John the Baptist where Benedictine monks cared for sick, poor, or injured Christian pilgrims to the Holy Land. Blessed Gerard , a lay brother of the Benedictine order, became its head when it was established. After the Christian conquest of Jerusalem in during the First Crusade , the Hospitallers rose in prominence and were recognized as a distinct order by Pope Paschal II in The Order of Saint John was militarized in the s and s, hiring knights that later became Hospitallers.
The organization became a military religious order under its own papal charter, charged with the care and defence of the Holy Land , and fought in the Crusades until the Siege of Acre in Following the reconquest of the Holy Land by Islamic forces , the knights operated from Rhodes, over which they were sovereign , and later from Malta, where they administered a vassal state under the Spanish viceroy of Sicily.
The Hospitallers were one of the smallest groups to have colonized parts of the Americas, briefly acquiring four Caribbean islands in the midth century, which they turned over to France in the s. The knights became divided during the Protestant Reformation , when rich commanderies of the order in northern Germany and the Netherlands became Protestant and largely separated from the Catholic main stem, remaining separate to this day ; modern ecumenical relations between the descendant chivalric orders are amicable.
The order was suppressed in England, Denmark, and other parts of northern Europe, and was further damaged by Napoleon 's capture of Malta in , after which it dispersed throughout Europe. About years later, in , the Fatimid caliph al-Hakim bi-Amr Allah destroyed the hospital and three thousand other buildings in Jerusalem.
