Ksar el Kebir (ksär ĕl kĕbĭrˈ) [key], city (1994 pop. 107,065), N Morocco. The name also appears as Alcazarquivir and Al Qasr al Kabir. Near the city on Aug. 4, 1578, the Moroccans soundly defeated the Portuguese. King Sebastian of Portugal had invaded Morocco in support of a pretender to the Moroccan throne. Abd al-Malik, ruler of Morocco, King Sebastian, and the Moroccan pretender, Muhammad, all died in the fighting. As a result of the battle, Portugal soon passed (1580) to Philip II of Spain, and the new Moroccan ruler, Ahmad al-Mansur, began his reign with tremendous prestige.