Complex sentence: On 22 September 1941 Merten torpedoed his first ship the British Steamer sailing in convoy SL-87 and on the 6 November 1942 he sunk his last ship the British Steamer, bringing his total to 27 ships of 170,151 gross tons.
Split into simpler sentences: On 22 September 1941, Merten torpedoed his first ship the British Steamer sailing in convoy SL-87. On the 6 November 1942 he sunk his last ship the British Steamer, bringing his total to 27 ships of 170,151 gross tons.