Complex sentence: Wheeler served in the Royal Navy as a Fleet Air Arm pilot, minesweeper captain and executive of a frigate, and his best selling novel "The Raging of the Sea", although a work of fiction it is based on his own personal experience.
Split into simpler sentences: Wheeler served in the Royal Navy as a Fleet Air Arm pilot, minesweeper captain and executive of a frigate, and his best known novel is "The Raging of the Sea". Although a work of fiction it is based on his own personal experience.