Complex sentence: In October 1942, he was given command of the 27th U-boat Flotilla, based in Gotenhafen (now Gdynia, Poland), which put him in charge of introducing the new Type XXI Elektro Boot boats to active service.
Split into simpler sentences: In October 1942, he was given command of the 27. Unterseebootsflottille, based in Gotenhafen (now Gdynia, Poland), which put him in charge of introducing the new Type XXI Elektro Boot boats to active service.