Complex sentence: During the 1980s, he was an important leader in the fight against Ethiopian dictator Mengistu Haile Mariam and when Mengistu was overthrown in 1991, Layne became acting Prime Minister and defense minister.
Split into simpler sentences: During the 1980s, he was an important figure in the fight against Ethiopian dictator Mengistu Haile Mariam. When Mengistu was overthrown in 1991, Layne became acting Prime Minister and defense minister.