The camp was named after Major General William George Haan of World War I.

The Attack on Pearl Harbor and the Battle of Los Angeles–Bombardment of Ellwood had put all of California on high alert.

[4] The winning of the North African campaign brought a number of Italian Prisoners of War (POW) to California.

At the end of the war, the camp was used for temporary housing of troop coming from Operation Magic Carpet.

[7][8][9][10] In 2023, a book titled "Camp Haan: Riverside's World War II Anti Aircraft Training Center" was released by Keith A. Beaulieu.