Complex sentence: In September 1942, a PBY Catalina, carrying top secret documents from England to Gibraltar, crashed off Cadiz with the loss of all lives, including Paymaster-Lt. James Hadden Turner, the courier and a French agent.
Split into simpler sentences: In September 1942, a PBY Catalina, flying from England to Gibraltar, crashed off Cadiz. All aboard were killed, including Paymaster-Lt. James Hadden Turner, a courier carrying top secret documents and a French agent.