Immediately after Algerian independence, Morocco laid claim to stretches of southern and western Algeria that had been under Moroccan sovereignty before the French gained control over the area in the nineteenth century. Other demands for adjustment, from Algeria's President Ahmed Ben Bella (1918-), were ignored and, in October 1963, Algerian and Moroccan forces began a border war in which many lives were lost. In a series of sharp engagements in the disputed territory in October 1963, the professional Moroccan army consistently outperformed Algerian regulars and local guerrillas. The fledgling Organization of African Unity (OAU), led by Ethiopian emperor Haile Selassie (1891-1975) and Mali's President Modibo Keita (1915-77), intervened and was able to arrange a cease-fire (February 20, 1964). But relations between Algeria and Morocco remained strained.