RAF Hercules crew signed cover 90th anniv of the World's First Ever Air Raid

RAF Hercules crew signed cover The World's First Strategic Bombing Raid by a Formation of Aircraft Belfort to Friedrichshafen 21 Nov 1914 COF 14 - 1914 cover signed A Ihlefeld, A Salam, GC Spreckley, JH Frank and MF Lavin RAF FDC.