With the declaration of war with Spain in April 1898, 164,932 National Guardsmen entered Federal service. The 1st New Mexico Cavalry entered Federal service as the 2nd Squadron, 1st U.S. Volunteer Cavalry, better known as the "Rough Riders." Theodore Roosevelt conceived the idea of raising a cavalry regiment recruited from businessmen, cowboys and outdoorsmen. Roosevelt, a former New York National Guardsman, helped to organize the regiment and was appointed its lieutenant colonel. After training in Texas and Florida, the Rough Riders landed in Cuba, without their horses, on June 22, 1898. It was during the Battle of San Juan Hill, on July 1, that the Rough Riders, under the command of Lt. Col. Roosevelt, made their mark in American military history. Ordered to seize Kettle Hill in support of the main attack, the Rough Riders fought their way to the top despite heavy enemy fire. New Mexico's E and G Troops were among the first to reach the top of Kettle Hill. After taking the hill, the Rough Riders continued their attack, seizing the heights overlooking the city of Santiago. The American victory led to the Spanish surrender two weeks later. The gallant heritage of the 2nd Squadron of the Rough Riders is perpetuated by the 200th Air Defence Artillery, New Mexico Army National Guard.