The Army was proud of its preparations to defend Hawaii. The Hawaiian Department was the Army's largest overseas department. For more than three decades, the War Department constructed elaborate coastal defenses on Oahu. The previous 18 months witnessed the arrival of the Pacific Fleet, war scares, the start of selective service, numerous training exercises, the mobilization of the National Guard, and the doubling of the department's strength to 43,000 soldiers (including the Army Air Corps). The Hawaiian Department's two primary tasks were to protect the Navy’s Pacific Fleet from sabotage and to defeat any invasion. In April 1941, Army Chief of Staff Gen. George Marshall assured President Roosevelt: "The Island of Oahu, due to its fortification, its garrison, and its physical characteristics, is believed to be the strongest fortress in the world."
Despite these preparations, war came suddenly to Fort Shafter on 7 December 1941. The new Hawaiian Department commander, Lt. Gen. Walter C. Short, had his headquarters at Fort Shafter. Lt. Gen. Short took command of the Hawaiian Department in February 1941 and moved into Quarters 5, the commanding general's residence on Palm Circle. On the morning of 7 December, he was preparing for his regular Sunday morning golf match with his Navy counterpart, Admiral Husband E. Kimmel, when he heard heavy firing from the direction of Pearl Harbor. He ordered his command to the highest alert and moved to his forward command post in Aliamanu Crater to direct the deployment of his command. He was relieved on 17 December 1941 and retired shortly afterward.
On 7 December, the Hawaiian Department suffered far fewer casualties than the Navy or Marines. In all, 228 soldiers were killed or died of wounds, 110 seriously wounded and 358 slightly wounded. Only 16 of the soldiers killed were not from the Air Corps. From Schofield Barracks, five soldiers were killed (only two by direct enemy action). At Fort Shafter, one soldier, Corporal Arthur A. Favreau from the 64th Coast Artillery (Anti-Aircraft), was killed in his barracks on post by an errant Navy shell. Fort Shafter quickly became a busy headquarters and the command converted the barracks on Palm Circle to offices. In 1944, the Army Corps of Engineers erected the "Pineapple Pentagon" (Richardson Hall and two other adjoining buildings) in just 49 days. Army engineers filled in two large fishponds to form Shafter Flats
USARPAC postures and prepares the force for unified land operations, responds to threats, sustains and protects the force, and builds military relationships that develop partner defense capacity in order to contribute to a stable and secure U.S. Pacific Command area of responsibility.
Vincent K. Brooks