revision preference src: The Ethiopian Civil War began on 12 September 1974 when the Marxist Derg staged a coup d 'e ́ tat against Emperor Haile Selassie. <SEP> tgt: While this was going on, there was also a civil war in Ethiopia, which began in 1974. <SEP> This war was started by a rebellion by the Marxist Derg to overthrow the Emperor Haile Selassie.