Hethum's gains against the Mamluks were short-lived, as in 1303, the Mamluks counter-attacked from Egypt. The Armenians again joined forces with a sizable number of Mongol troops, 80,000, on a Syrian offensive, but they were defeated at Homs on March 30, 1303, and at the decisive Battle of Shaqhab (Merj-us-Safer), south of Damas, on April 21, 1303. This campaign is considered to be the last major Mongol invasion of Syria. Hethum retreated to Ghazan's court in Moussoul, and then again resigned his crown. His brother Thoros III having been killed in 1298, Hethum passed the crown to Thoros's teenaged son, Leo III. Hethum retired to a monastery, although as Leo was not yet an adult, Hethum retained the office of Regent of Armenia.