Several of these companies formed the 12th Regiment, Vermont Volunteers, organized from 12 August-25 September 1862 and mustered into federal service 4 October 1862 at Brattleboro.

[citation needed] Mustered into Federal service 22 June 1916 at Fort Ethan Allen, Vermont; mustered out of Federal service 9-11 October 1916 at Fort Ethan Allen, Vermont (Company B mustered into Federal service 30 March 1917 at St. Albans) Regiment (less Company B) mustered into Federal service 10 April 1917 at Fort Ethan Allen, Vermont; drafted into Federal service 5 August 1917 (1st Regiment, Vermont State Guard, organized 27 June 1917 to replace regiment in Federal service) Reorganized and redesignated 9 February 1917 as the 57th Pioneer Infantry Demobilized 4 March 1919 at Camp Devens, Massachusetts Consolidated 20 June 1917 with the 1st Regiment, Vermont State Guard, and with Companies D, E, and F, 101st Ammunition Train (organized 27 August 1917 from personnel of the 1st Infantry Regiment [Vermont] and elements of the Coast Artillery, Massachusetts National Guard, and assigned to the 26th Division; demobilized 3 May 1919 at Camp Devens, Massachusetts) and consolidated unit reorganized in the Vermont National Guard as the 1st Infantry.

On 25 June 1919, the headquarters of the 1st Infantry Regiment, Vermont National Guard was organized and federally recognized at Brattleboro.

[citation needed] The initial assignment of the "172nd" designation to a unit of the Vermont National Guard by the War Department can be traced to 1 October 1921.

The regimental headquarters was relocated to St. Johnsbury, on 1 January 1929, to Northfield on 17 July 1930, to Rutland on 16 February 1933, to Bennington, on 1 September 1938, and back to Brattleboro in 1940.

Regimental elements were called up for riot control during labor troubles at paper mills in Bellows Falls and Wilder from 25 July–5 August 1921, flood relief duty at Waterbury and Montpelier, from 3–21 November 192, riot control during a granite workers’ strike at Barre, 8 May–3 June 1930, and the 3rd Battalion performed flood relief duty at Bennington, Windsor and Brattleboro from 18–22 March 1936.

The new RCT comprised the 172nd Infantry Regiment, the 103rd Field Artillery Battalion and parts of ordnance, engineer, medical and signal units.

[8] The 172nd RCT almost saw disaster at Espiritu Santo, New Hebrides on 26 October 1942, when its troop transport, the liner SS President Coolidge, struck two U.S. mines in the harbor.

The ship sank, but the regiment got ashore with few casualties, to fight in the New Georgia Campaign, including during the Drive on Munda Point.

[2] Battle honors earned by the current 172nd Cavalry and previous or consolidated units:[citation needed]