The World War II army of the US is the biggest army in history.

Due in part to the surge of wartime patriotism, and in part because of conscription, the US Army numbered 12,000,000 soldiers by the end of the war in 1945.

By 1943, the German military had reached 11,000,000 soldiers.

By the end of the war, the Soviet Union’s army (as formidable as it was) also reached 11 million soldiers.