Australia and the South Pacific
The same month Dewey transferred to the Army Air Corps to begin his pilot training, December 1941, aircraft carrier-based bombers of the Imperial Japanese Navy attacked the U.S. Army and Naval bases at Pearl Harbor, Hawaii on December 7th. The following day the United States declared war on the Japanese Empire, entering the conflict on the side of the Allied Nations against the Axis Powers: Imperial Japan, Nazi Germany, and Fascist Italy. The Second World War was now truly a global war, with the United States fighting in both hemispheres.
Over the next six months, Imperial Japanese forces conquered much of the South Pacific region, including the Dutch East Indies (today Indonesia), the Philippines, and New Guinea, as well as many island nations and small atolls across the vast ocean. The American victory at the Battle of Midway in June 1942 was a major turning point in the Pacific war; after Midway, the Empire was on the defensive. In August, U.S. Marines landed on Guadalcanal in the Solomon Islands, while Australian and American forces began the drive to liberate East New Guinea (today the country of Papua New Guinea), supported by aircraft operating from Australia.
The map below shows the approxomite location of the Iron Range airfield, in Queensland, where Dewey Hooper was stationed; zoom out on the marker to see more detail and the surrounding region of the South Pacific.