The Boeing B-17 Fortress, the classic American bomber of World War II, was relatively new in service at the outbreak of the war. The B-17C (Fortress I) which was introduced in 1941 was powered by four 1,200 horsepower Wright R-1820-65 engines asn was armed with seven 30 caliber guns. Only a dozen were at Hickam Field on the morning of 7 December, and more were being flown in that morning under the command of Major Truman Landon (Landon, Truman). They arrived as the attack was in progress and, in spite of the fact that the Japanese had no four-engined bombers, came under fire from their friends. The length of the flight from the mainland was so great that the aircraft were lightened as much as possible and were therefore unarmed and unable to defend themselves. American operation of radar was immature on Oahu and the echo of the incoming Japanese was dismissed as being that of the B-17s.