Complex sentence: In September 1944, he and an RAF officer crawled under the wire through an abandoned drain and set out to walk to the Baltic coast; they were recaptured near the coastal city of Rostock, only a few miles from the sea.
Split into simpler sentences: In September 1944, he and a Royal Air Force officer crawled under the wire through an abandoned drain and attempted to walk to the Baltic coast. They were recaptured near the coastal city of Rostock, a few kilometres from the sea.