Complex sentence: Belev was forced to resign from his position in September, 1943 by the newly-appointed Prime Minister Dobri Bozhilov and was replaced with the more moderate Christo Stomanyakov.
Split into simpler sentences: Belev was forced to resign from his position in September, 1943 by the newly-appointed Prime Minister Dobri Bozhilov. He was replaced with the more moderate Christo Stomanyakov.