 The origins of the Knights Hospitaller are unclear , but the order probably emerged around the <unk> in Jerusalem . It started as a religious order which cared for the sick , and later looked after pilgrims to the Holy Land . After the success of the First Crusade in capturing Jerusalem in 1099 , many crusaders donated their new property in the Levant to the Hospital of St John . Early donations were in the newly formed Kingdom of Jerusalem , but over time the order extended its holdings to the Crusader states of the County of Tripoli and the Principality of Antioch . Evidence suggests that in the <unk> the order became <unk> when Fulk , King of Jerusalem , granted the newly built castle at <unk> to the order in 1136 . A papal bull from between 1139 and <unk> may indicate the order hiring people to defend pilgrims . There were also other military orders , such as the Knights Templar , which offered protection to pilgrims . 
