Steichen, who had come to regard France as a second homeland, was quick to enlist once the U.S. officially entered the war in 1917. Though at 38 he was eight years older than the age limit set by the Signal Corps, his experience as a photographer made him a valuable recruit, and he entered active duty in July 1917 as a first lieutenant.
The First World War, sometimes called the first “modern” war, was marked by groundbreaking advances in technology, including photography. Though Steichen intended to be “a photographic reporter, as Mathew Brady had been in the Civil War,” he quickly abandoned this romantic notion to help implement one of the newest weapons of war—aerial photography. Taking images from airplanes made it possible not only to observe a wide swath of the battlefield, but also to track daily changes on the front lines.
The French and British militaries had made great advances with this technology for intelligence purposes, yet the American Expeditionary Forces (AEF) had no established program. Steichen was assigned to the newly formed Photographic Section, led by Major James Barnes, and together they oversaw the training and outfitting of aerial-photography and surveillance units that would prove their usefulness over the course of the war. Steichen also worked to standardize print sizes, materials, cameras, and plates across the various national armies in order to simplify the cooperation between the Allied forces.
 Edward Steichen, A Life in Photography (Doubleday, 1963), chap. 5, n.p.