Beginning in October 1943, launch sites for the V-1 were constructed in Northern France, along the coast from Calais to Le Havre. Aerial bombing attacks on these sites by the Allied airforce were only partially successful, and by June 1944 they were ready for action.[12] Prompted by the Normandy Landings of 6 June, in the early morning of 13 June 1944, the first V-1 flying bomb attack was carried out on London.[2][13] Ten missiles were launched, of which four reached England.