The Battle of Hawaii was the first major land, sea and air engagement of Great Patriotic War. The Japanese struck with a force of six fleet carriers and an invasion force of 2 Infantry divisions. The first phase of the invasion involved a massive coordinated air strike against US military targets on Hawaii, followed up by the first major naval battle in the Pacific. After the Japanese defeated the US Navy, the 25th Army, under General Yamashita landed on the Northern tip of Oahu, and pushed south, before finally forcing the US Army to surrender upon reaching the outskirts of Honolulu. This was the first major defeat the US had suffered, and resulted in US forces pushed back to their own west coast.
In January 1942, an American task force attempting to invade Oahu is defeated when the Japanese make use of captured American radar systems from Hawaii, and the carriers USS Yorktown and Saratoga are lost while the USS Hornet is badly damaged.
With the United States' main forward base in the Pacific conquered, this allows Japan to dominate much of the southern Pacific Ocean almost unopposed from successfully defeating the British in the Indian Ocean, occupying all of New Guinea and the Dutch East Indies, attacking Australia, capturing Wake and Midway Islands, and having the ability to launch bombing raids on the West Coast of the United States.
In the United States, the Americans have amassed the ships and troops to retake Hawaii, and launch invasion attempt. The Americans quickly gain the upper hand, torpedoing the Japanese carrier Zuikaku with a submarine, and sinking the Akagi and Shōkaku in aerial attacks at the loss of only one escort carrier. The Americans, greatly aided by their new F6F Hellcatfighter, quickly gain control of the air, and gradually defeat the Japanese on Oahu.