In June 1940, Congress authorized funding for the purchase of property in coastal Georgia for the purpose of building an anti-aircraft artillery training center. It was to be located just outside of Hinesville, Georgia, some 40 miles (64 km) southwest of Savannah
On 1 July 1940 the first 5,000 acres (20 km²) were bought and subsequent purchases followed. Eventually the reservation would include over 280,000 acres (1100 km²) and stretch over five counties. The large expanse of property was required for the firing ranges and impact areas which an anti-aircraft artillery training center would need for live-fire training.
Fort Stewart was established in September 1940 as the Anti-Aircraft Artillery Training Center. The first unit to arrive was the 70th Coast Artillery Regiment. It was designated Camp Stewart on 10 Jan 1941, after Brigadier General Daniel Stewart, a Liberty County Revolutionary War hero.
In fall of 1941, the Carolina maneuvers were held, and all the anti-aircraft units from Camp Stewart participated. As these maneuvers drew to a close, a feeling of restless anticipation pervaded the ranks of the National Guard soldiers who were looking toward their impending release from active duty, after completion of their year of training. However, the Japanese attack on Pearl Harbor on December 7th ended these dreams. Now the U.S. was in the war, and Camp Stewart set about accomplishing the mission it was intended for.
In the fall of 1941 Camp Stewart troops participated in the Louisiana Maneuvers, the largest peacetime field operation undertaken up to that time. By June 1942 twenty-one battalions were on post taking anti-aircraft training with training reaching its peak in the spring of 1943 when over 40,000 men were on Camp Stewart.
During World War II, 151 Anti-Aircraft Artillery battalions would train at Camp Stewart. The camp served as a holding area for German and Italian Prisoners of War during World War II. It also boasted a Cooks and Bakers School, one of the earliest Women's Army Corps detachments and even Women Air Force Service Pilots unit which ferried aircraft for the Army Air Corps.
During the early months, training was done on wooden mock-ups, since real anti-aircraft guns were in short supply. Live-firing exercises were conducted on the beaches of St. Augustine and Amelia Island, Florida, since the necessary ranges and impact areas had not been completed at Camp Stewart. This live-fire training over the ocean continued until September 1941, while at Camp Stewart practice firing and searchlight training progressed.
Savannah's First Bryan Baptist Church had a special service for soldiers from the Savannah Air Base and Camp Stewart December 21, 1941. Reverend Terrill wrote a letter to Asa H. Gordon, director of the Colored SSSS, extending the invitation to the soldiers. Church members took at least one soldier home from the service for Sunday dinner. Reverend Terrill, at the special service for soldiers, preached on "The Negro's Place in National Defence." Thelma Lee Stevens gave the welcome address. Scout Westley W. Law was master of ceremonies (source: page 71, Dr. Charles J. Elmore, "First Bryan 1788-2001 The Oldest Continuous Black Baptist Church in America.")
The National Guard units departed and new units came in for training. Facilities were expanded and improved. Anti-aircraft artillery training was upgraded and soon a detachment of Women’s Air Service Pilots (WASP’s) arrived at the air facility on post, Liberty Field, to fly planes to tow targets for the live-fire exercises. Eventually radio-controlled airplane targets came into use as a more effective and safer means of live-fire practice.
As the war progressed, Camp Stewart’s training programs continued expanding to keep pace with the needs placed upon it. Units were shipped out promptly upon completion of their training, and new units received in their place. The camp provided well-trained soldiers for duty in the European, the Mediterranean, the North African, and the Pacific Theaters.