Fill The Blank!! In the Pacific, the Allies focused on attacking ___ first

In June 1942, the United States defeated Japan in the battle of ___ .

By February 1945, the Allies had captured ___. and were using it as an airbase.
First Blank: strategic islands, Japans mainland, a Hawaiian naval base
Second Blank: Iwo Jima, Midway, Stalingrad
Third Blank: Iwo Jima, Midway, Stalingrad