Complex sentence: During this trip, the U- 180 was supplied by the U- 462 submarine on the way to the exchange, and was supposed to be refueled by the U- 463 on the way back, but she was sunk by the British in May, 1943.
Split into simpler sentences: During this trip, the U- 180 was supplied by the U- 462 submarine on the way to the exchange. She was supposed to be refueled by the U- 463 on the way back, but U- 463 was sunk by the British in May, 1943.