Southern Defense Command (SDC) was established on 17 March 1941 as the command formation of the U.S. Army responsible for coordinating the defense of the Gulf of Mexico coastal region of the United States. A second major responsibility of SDC was the training of soldiers prior to their deployment overseas. The first Commanding General of SDC was Lieutenant General Herbert Brees, who simultaneously commanded the Third Army. General Brees retired due to age in May 1941, and was replaced by Lieutenant General Walter Krueger, who held both posts until January 1943. SDC headquarters was co-located with the existing Third Army headquarters at Fort Sam Houston. SDC's operational region covered the states of New Mexico, Texas, Oklahoma, Arkansas, Louisiana, Mississippi, Alabama, Tennessee, and the