At 7 AM on the morning of December 7, 1941 the U.S. Army Air Force had 152 fighters in the fifteenth and eighteenth Pursuit Group deployed for air defense of Hawaiian island of Oahu, and 57 bombers that could hunt enemy ships.
In the following two hours, two-thirds of these aircraft would be damaged or destroyed and four of the battleships they were there to protect sunk at the bottom of Pearl Harbor.
But at least fourteen U.S. Army fliers did manage to intervene in the skies over Oahu—too few to stop the relentless aerial assault, they nonetheless fought their overwhelming assailants tooth and claw.
The failure of U.S. air defenses at Pearl Harbor reflected a systemic communication breakdown the military and Washington. The White House was amply warned Japan might attempt some kind of attack due to its need to secure oil wells after Roosevelt imposed an embargo on the expanding empire. Washington warned U.S. forces in the Pacific to prepare for war and dispatch reinforcements to exposed garrisons in the Philippines and Wake island.
But Army and Navy leaders in Hawaii did not realize Pearl Harbor itself might be in range of an attack. Army Lt. Gen. Walter Short assumed the threat came from clandestine sabotage, so he ordered the aircraft in Hawaii lined up wingtip-to-wingtip in the open. After a week on alert, he gave Army units the weekend off to boost morale.
Still, the threat of war was palpable. On the evening of December 6, while seeing off the 38th and 88th Reconnaissance squadrons as they prepared to fly their B-17s from Hamilton Field, California to Hawaii, Air Force chief General ‘Hap’ Arnold told the pilots “War is imminent. You may run into a war during your flight.”
When at 7 AM on December 7 technicians manning the Army’s new SCR-270 radar at Opana Point detected some of the 183 Imperial Japanese Navy warplanes inbound for Pearl Harbor, their untrained commanding officer assumed the contacts were the B-17s due to arrive.
In fact, the B-17Cs and Es were approaching Hawaii from a virtually identical trajectory and bumped into some of the 41 A6M Zero fighters tasked with providing air cover and strafing parked aircraft.