Complex sentence: The troops had been the subject of regular racial abuse by some of their white officers, and the rumour that a black sergeant had died at the hands of a white superior resulted in the troops of A and C company mutinying.
Split into simpler sentences: The troops had been the subject of regular racial abuse by some of their white officers. A rumour that a black sergeant had died at the hands of a white superior resulted in the troops of A and C company mutinying.