 One year later, Eagles was ordered to Fort Sam Houston, Texas, where he joined the headquarters of 8th Corps Area under Major General Herbert J. Brees as Officer-in-Charge of Supply, Construction & Budget.He was promoted to lieutenant colonel on July 1, 1940.By the beginning of November 1940, Eagles was attached to the headquarters, VIII Corps under Major General George V. Strong located also at Fort Sam Houston and was promoted to the temporary rank of colonel on December 11, 1941, just four days after the Japanese Attack on Pearl Harbor and the United States entry into World War II.