Japanese Internment Camps - The Japanese Internment Camps were set up to house Japanese-Americans who were American citizens. The were similar to Nazi concentration camps. Why were American citizens forced to live in these camps following Pearl Harbor?
What affect did D-Day (June 6, 1944) have on the war in Europe?
Why were the battles of Iwo Jima and Okinawa so bloody for the Americans in these battles?
How did air-power help win WW2 in Europe and in the Pacific?
Go for something different than the same old stuff that everyone just repeats endlessly. There are lot's of small but interesting campaigns/battles that rarely get mentioned.
US fighters and bombers flying in defence of the Dutch East Indies in 1942
Battle of Sunda Straight - The cruisers USS Houston and HMAS Perth going down fighting against a Japanese Invasion fleet.
The Aleutians Campaign - The only part of North America occupied during the war.
Japanese air raid on mainland and US attempting to start fires in the Oregon forest.
Meeting of US and Soviet troops in Germany at Torgau in 1945