In March 1917, before U.S. entry into World War I, Major General John J. Pershing chose Mercedes as the site of a permanent camp to train personnel for overseas service in France. Construction of Camp Mercedes on the 80-acre Emerson Farm tract southeast of town was completed in April 1917. The post centered on a parade ground lined by 23 barracks buildings and 14 look-alike officers bungalows, and its strength was 16 officers, 700 men, and 600 horses. A training cadre from the 16th Cavalry under Colonel W.S. Scott occupied Camp Mercedes in May before the first recruits arrived on May 17. After the Armistice, the unit was demobilized and Camp Mercedes closed in 1922.