How many Americans fought in Europe in World War 2?

OVER 16,000 US Servicemen were in uniform during WW2. Approximately 11 million men were in the US Army. The remaining 4 plus million men were in the US Navy (the Marines are (and were) part of the US Navy...500,000 (half a million) men were in the US Marine Corps); the US Air Force did NOT EXIST, US Airmen were part of the US Army. Consequently, the 11 million men in the above figures for the Army is counting the AIR FORCE/AIR CORPS.

WW2 consisted of TWO Wars; the Land war in Europe, and the Ocean War in the Pacific. The majority of the US Army was in Europe. Token forces of US Navy, and US Marine Corps were in Europe.

The majority of the US Navy and US Marine Corps fought under Admiral Nimitz in the Central Pacific. US Army General MacArthur's command in the South Pacific, General Wainwright's command, General Stillwell's command (CBI Theater), and General Simon Buckner's 10th Army were well engaged in the Pacific also.