1935 1st Cavalry Division is dismounted and mechanized.
1941 11th Cavalry is the last US Army unit to loose their mounts and become a mechanized unit.
7 Dec 41 The Japanese attack on Pearl Harbor pushes the U.S. into a war for which it is not ready. Astounded Americans unite behind President Roosevelt. Enlistments exceed the capacity of the armed forces to handle them. The barracks at Fort Lewis fill rapidly, and soon the Army is considering activating another two battalions of the 87th Mountain Infantry.
2 Nov 42 10th Cavalry Reconnaissance Troop, recently formed as a cavalry unit at Fort Meade, SD, arrives at Camp Carson, CO, for training under the command of the MTC. Before long, the troop will be known as the “10th Recon.”
25 April 43 The 10th Recon’s combat mission is re-defined as mechanized reconnaissance in mountain terrain. To accomplish its training mission, cavalrymen will be replaced with expert skiers and mountaineers, and the animals by mechanized equipment. The troop will provide instructors for training others in the Mountain Training Group (MTG), and will soon provide mountain and winter warfare training to the 10th Light Division and other units throughout the country.
21 Jul 43 32 rock-climbing instructors of the 10th Recon are sent to Elkins, WV. Other detachments are soon sent to Fort Lewis, WA, Watersmeet, MI, Camp McCoy, WI and other locations.
30 Aug 43 10th Recon establishes a rock climbing school for the 10th at Homestake Creek.
26 Oct 43 Back at Camp Hale, the MTG is formed. For the next five months, the MTG and the 10th Recon will share the task of providing mountaineering training.
21-25 Feb 44 The 10th Recon makes a long trek on skis and horseback from Leadville to Aspen Crossover, one of several such mountaineering exercises conducted during the winter of 43-44.
21 Mar 44 The 10th Recon is inactivated. Its seven officers and 142 enlisted men are transferred to the MTG, which, in turn, transfers most of its personnel to line companies in the division.
20-24 Jun 44 In Colorado, the 10th Light Division leaves for Camp Swift, Texas for flatland training. The aim is to prepare the division for maneuvers in Louisiana. But with the Army’s attention now on the European battlefield, these maneuvers are canceled. Rumors that the 10th will fight in Southeast Asia are fueled when some units are given maps of Burma to study. Others receive Japanese language phrase books. While in Camp Swift, recruits approved by the National Ski Patrol continue to join the division. But now their basic training takes place at locations other than Camp Hale.
6 Nov 44 The 10th Light Division is renamed the 10th Mountain Division and reorganized as a “Modified Triangular Division,” i.e., each of three infantry regiments now has 12 line companies, including one heavy weapons company in each battalion (D, H, or M). The 10th Mountain Cavalry Reconnaissance Troop is re-activated—but unlike the unit with the same name at Camp Hale, the newly formed unit is mounted on horseback only (as it will be in Italy), and comes to be known as the "10th Cavalry".