After the Farewell Pilgrimage in 632, the Prophet Muhammad appointed Usama ibn Zayd as the commander of an expeditionary force which was to invade the region of Balqa in the Byzantine Empire. This expedition was known as the Expedition of Usama bin Zayd and its stated aim was to avenge the Muslim losses at the Battle of Mu'tah, in which Usama's father and Muhammad's adopted son, Zayd ibn Harithah, had been killed. Usama's expedition in May/June 632 was successful and his army was the first Muslim force to successfully invade and raid Byzantine territory.