In the early spring of 1940, the US military faced a seemingly insurmountable task. With Poland overrun by German armored columns now poised to strike at France, and China under assault by Japan, America’s commanders had to prepare the US military for war. The problem was not a dearth of troops—after Adolf Hitler’s blitzkrieg rolled through Poland in September 1939, Congress had mobilized the National Guard and Reserve and approved an increase in the size of the Army. It was that the existing troops were poorly trained or not trained at all. No one was more acutely aware of this than Army Chief of Staff General George C. Marshall. A student of history, Marshall was certain American boys were as courageous as any German or Japanese soldier, but they lacked sufficient training and combat experience—and time was short. Marshall concluded that what America’s burgeoning ranks needed was a complex training exercise, an exacting test in an environment that would closely approximate the realities of the battlefield.

—“Louisiana Maneuvers” by Mark Perry

What was General Marshall’s biggest concern about the US Army in 1940?

There were not enough soldiers enlisted in the military.
Most soldiers had received little preparation on how to fight a war.
There was no land available to complete combat training exercises.
American troops were already struggling in the fight against Germany.