Complex sentence: These were completed by 15 December 1943, and the ship then returned to Britain, but she did not become fully operational again until early June 1944, when she immediately sailed for the invasion of Normandy, forming part of Force "D" off Sword Beach.
Split into simpler sentences: These were completed by 15 December 1943, and the ship then returned to Britain. She did not become fully operational again until early June 1944, when she sailed for the invasion of Normandy, forming part of Force "D" off Sword Beach.