born 1937, Kefa province, Eth. Ethiopian army officer and head of state (1974-91). Mengistu headed a group of rebel soldiers that overthrew Haile Selassie (1974). After assassinating his rivals, Mengistu became the new regime's acknowledged strongman. By 1978 he had crushed a major rebellion in Eritrea and, with Soviet and Cuban help, an invasion of the Ogaden region by the Somalis. In the 1980s he faced new rebellions in Eritrea and Tigray, and devastating droughts and famines drew attention to his failed agricultural policies. With the withdrawal of Soviet support in 1991, his power was weakened and he fled to Zimbabwe