bigpigeon.us webpage  WW II -  Japan >  Iwo Jima & Okinawa, updated by RAC 11 Sep 2020.

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Background - The War in the Pacific - Early 1945

The accompanying map, despite the caption date, shows the Pacific Theater in mid-January, 1945. Leyte and Mindoro have been recaptured. Luzon, the main Philippines island, has just been invaded by the U.S. Army.

As a large portion of the US Army in the Southwest Pacific continued the Philippines campaign, preparations were underway for the last two major Pacific Theater battles, namely Iwo Jima and Okinawa, shown south of the Japanese Home Islands.

The battles of Iwo Jima and Okinawa comprised the  Volcano and Ryukyu Islands Campaign from February to June 1945. These battles were enormously costly in terms of American lives lost. These battles saw the increased use of kamikaze aircraft.
The Pacific Theater, mid-January 1945
The Pacific Theater - mid-January 1945
Ulithi was the forward base for the huge US Pacific Fleet, which supported both the Iwo Jima and Okinawa campaigns. Ulithi had been abandoned by the Japanese and then occupied by US forces in September 1944. In provided a magnificant anchorage for a large fleet, but very little dry ground. Although Japanese forces still occupied Yap, west of Ulithi, and the remaining Caroline Islands to the southeast, Japanese naval and air power, now largely destroyed, did not pose a substantial threat to the fleet at Ulithi.