Knight Hospitaller - Order of Saint JohnThe Order of Knights of the Hospital of Saint John of Jerusalem, commonly known as the Knights Hospitaller or the Order of Saint John, was a medieval and early modern Catholic military order . 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 Hospitallers arose in the early 11th century, at the time of the great