Roger was part of the Battle of Montgisard (pictured) against the Ayyubid Sultanate (the dynasty founded by Saladin when he came to power. The fighting was fierce: Roger's own report was that 1100 men had been killed and a further 750 wounded. It was one of Saladin's few defeats, and completely redeemed by the Battle of Hattin ten years later.
The full name of the Hospitallers was Order of Knights of the Hospital of Saint John of Jerusalem. They had founded a hospital for the care of the sick and wounded in Jerusalem in 1113. The Order's increasing involvement in military affairs made them well-known and powerful, but distracted them from their original purpose. Their second Grandmaster, Raymond de Puy, had started them on a more military bearing.
Pope Alexander III issued a papal bull, declaring that they were not allowed to fight anyone unless attacked and urging the Order to focus on caring for the sick and the poor. Alexander also urged the Order to forget their rivalry with the Templars for the sake of unity in the Holy Land. The two Orders soon got together to negotiate a truce. The Orders, however, retained their rivalry.
Roger traveled Europe along with his Templar counterpart, Arnold of Torroja, and the Patriarch of Jerusalem Heraclius, to persuade Pope Lucius III and European nobles to form a new Crusade for the support of the Holy Land. Roger also intended to establish the Hospitallers in England, France, and Germany.
Arnold died along the way. Roger clashed with Arnold's successor, Gerard de Ridefort, Templar and Marshall of the Kingdom of Jerusalem who supported Guy of Lusignan as husband for Queen Sibylla of Jerusalem. Roger had been given the privilege of holding the key to the royal treasury, and at first refused to turn it over to Guy when Guy was crowned King of Jerusalem.
In 1182, Roger made a significant and interesting change in the Order's statutes that changed the atmosphere surrounding it. I'll explain more tomorrow.