On 10 May 1917, President Woodrow Wilson named Major General John J. “Blackjack” Pershing as the commander of the American Expeditionary Force (AEF) to France to fight alongside the Allies in the Great War in Europe. Pershing at the time was the commander of the US Southern Department, and because of his Expedition in Mexico to capture the outlaw Pancho Villa, was the only officer in the US Army that commanded a unit larger than a regiment. That his command was also deep in foreign territory which gave him a unique insight into the political and logistical difficulties of such an endeavor, only convinced President Wilson that Pershing was the right man to select, despite many more senior officers. He was promoted to full general, the first since Phillip Sheridan in 1868, and given wide latitude to organize and train the AEF.

At the suggestion of the Marshal Joffre, the victor of the Battle of the Marne and part of a French delegation to assist America’s entry into the war, Pershing was ordered to select four infantry regiments and an artillery regiment to constitute a division for immediate deployment to France. It would take at least a year to raise and train the numbers of American troops needed on the Western Front, but the initial arrival of even a token force would boost the flagging morale of the Allies. (The closest the Allies came to defeat on the Western Front occurred in May of 1917 after the failed Nivelle Offensive. The French Army suffered widespread mutinies, but the Germans failed to take advantage of the situation.) For two weeks, Pershing built his staff, and working with the British and French delegations, reorganized the American formations to better reflect the modern realities of fighting on the Western Front.

On 24 May 1917, Pershing chose regiments that he was experienced with from his Southern Department for the new division: the 16th, 18th, 26th, and 28th Infantry Regiments and the 6th Artillery Regiment. The new “First Expeditionary Division” was placed under the command of a well-respected engineer officer (and builder of the Panama Canal) Brigadier General William Sibert. Pershing took a direct hand in choosing most of Sibert’s staff and subordinate commanders, including but definitely not limited to: Colonel Robert Bullard, the commander of the 2nd Brigade, Major Theodore Roosevelt Jr., the commander of the 1st Battalion 26th Infantry and former president’s son; Major Leslie McNair, the Assistant Chief of Staff for Training; Major George C Marshall, the Assistant Chief of Staff for Operations; and Colonel Campbell King, a trusted infantry officer to serve as Sibert’s Chief of Staff. Sibert, to his credit, protested his appointment as division commander because he was not a line infantry officer, but was overruled due to the need for his experience. He was singularly qualified for transporting the division’s units from the American Southwest to New Jersey and eventually France, and the building the facilities and expansion of regiments to transform them into a “Square Division”.