'Conebo' was a British air undertaking by Bristol Beaufighter heavy fighters of Air Chief Marshal Sir William Sholto Douglas’s RAF Coastal Command to blockade the eastern end of the English Channel during 'Overlord' and so deny the German navy any opportunity to launch a naval attack on 'Overlord', especially by S-boote from bases in the German-occupied Low Countries, but also larger warships from German and Scandinavian ports (June 1944).