His marriage to Eschiva of Ibelin (whose father was an influential nobleman) strengthened his position in the kingdom. His younger brother, Guy, married Sibylla, the sister of and heir presumptive to Baldwin IV of Jerusalem. Baldwin made Aimery the constable of Jerusalem at around 1180. He was one of the commanders of the Christian army in the Battle of Hattin, which ended with decisive defeat at the hands of the army of Saladin, the Ayyubid sultan of Egypt and Syria, on 4 July 1187.