Complex sentence: Instead, he was visited by Lord Louis Mountbatten, the commander of the flotilla that sank his submarine, who arranged for the Admiralty to allow Lott and his second-in-command to dine at Scott's Restaurant on the condition they not try to escape.
Split into simpler sentences: Instead, he was visited by Lord Louis Mountbatten, who was the commander of the flotilla that sank his submarine. The Admiralty allowed him and his second-in-command to dine at Scott's Restaurant on the condition they not try to escape.