The Boeing B-17, which has come to epitomise the American war effort in Europe, took the fight to the German Air Force from the late summer of 1942 through to VE-Day. Its primary operator in Western Europe was the 'Mighty Eighth', who controlled 27 bomb groups for much of the war. Over 12,000 Fortresses were built. They were mainly deployed in Europe, flying from the 8th Air Force in England and the 15th Air Force in the Mediterranean. Their only form of defence was to fly in a tight formation and outgun any attacking Luftwaffe fighters by bringing their massive firepower to bear on intruders.