When war broke out in Europe and Asia in 1939, the War Department suggested to the National Guard that their 111th Cavalry convert to another branch of service. The age of the horse as a combatant had passed. Thus, the officers and non-commissioned officers of the command jointly selected coast artillery. In 1940, the 111th was re-designated the 200th Coast Artillery Regiment (AA) and the 158th was reorganized as the 104th Anti-Tank battalion. On January 6, 1940, these units, along with the 120th Engineer Regiment, were called to active duty for a one-year training period that became the prelude to some of the earliest combat experienced by American troops in World War II.
New Mexico in the 1940s also began to play a critical role in the emerging relationship between science and the military, which would grow rapidly in the decades to follow. This started with the testing of the variable-timed, radio, proximity-fused artillery shells that would be crucial to protecting the Navy's ships from Kamikazes and to the Army's defense of Bastogne, Belgium in 1944. Airplanes were suspended over the desert mesa near Kirtland between the tallest wooden towers in the world and used for targets.
The importance of the proximity fuze to the successful outcome of the Second World War is best stated by those who witnessed its effectiveness.
James V. Forrestal, Secretary of the Navy said, "The proximity fuze has helped blaze the trail to Japan. Without the protection this ingenious device has given the surface ships of the Fleet, our westward push could not have been so swift and the cost in men and ships would have been immeasurably greater."
Prime Minister, Winston S. Churchill was quoted with "These so-called proximity fuzes, made in the United States. . , proved potent against the small unmanned aircraft (V-1) with which we were assailed in 1944."
And Commanding General of the Third Army, George S. Patton said, "The funny fuze won the Battle of the Bulge for us. I think that when all armies get this shell we will have to devise some new method of warfare."