

In 800, Emperor Charlemagne enlarged Probus' hospital and added a library to it. In 603, Pope Gregory I commissioned the Ravennate Abbot Probus, who was previously Gregory's emissary at the Lombard court, to build a hospital in Jerusalem to treat and care for Christian pilgrims to the Holy Land. By virtue of this document, the pope officially recognized the existence of the new organisation as an operative and militant part of the Roman Catholic Church, granting it papal protection and confirming its properties in Europe and Asia. John of Jerusalem, which was to transform what was a community of pious men into an institution within the Church.

Bull issued by Pope Paschal II in 1113 in favor of the Order of St. The order was suppressed in England, Denmark, and some other parts of northern Europe, and it was further damaged by Napoleon's capture of Malta in 1798, following which it became dispersed throughout Europe.

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 Roman Catholic main stem, remaining separate to this day, although ecumenical relations between the descendant chivalric orders are amicable. The Hospitallers were one of the smallest groups to briefly colonize parts of the Americas: they acquired four Caribbean islands in the mid-17th century, which they turned over to France in the 1660s.

Following the conquest 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 organization became a military religious order under its own papal charter, charged with the care and defense of the Holy Land. Some scholars consider that the Amalfitan order and hospital were different from Gerard's order and its hospital. After the conquest of Jerusalem in 1099 during the First Crusade, a group of Crusaders formed a religious order to support the hospital. Early in the 11th century, merchants from Amalfi founded a hospital in the Muristan district of Jerusalem, dedicated to John the Baptist, to provide care for sick, poor, or injured pilgrims to the Holy Land. The Hospitallers arose in the early 12th century, during the time of the Cluniac movement (a Benedictine Reform movement). John, which are the Sovereign Military Order of Malta, the Most Venerable Order of the Hospital of Saint John, the Bailiwick of Brandenburg of the Chivalric Order of Saint John, the Order of Saint John in the Netherlands, and the Order of Saint John in Sweden. Today several organizations continue the Hospitaller tradition, specifically the mutually recognized orders of St. It was headquartered in the Kingdom of Jerusalem until 1291, on the island of Rhodes from 1310 until 1522, in Malta from 1530 until 1798 and at Saint Petersburg from 1799 until 1801. The Order of Knights of the Hospital of Saint John of Jerusalem ( Latin: Ordo Fratrum Hospitalis Sancti Ioannis Hierosolymitani), commonly known as the Knights Hospitaller ( / ˈ h ɒ s p ɪ t əl ər/), was a medieval and early modern Catholic military order.
