The American cavalry was officially created by an Act of Congress in 1833, although at times prior to this there had been various irregular mounted formations in U.S. service. The American concept of cavalry differed from the European in that the American troopers were not trained or equipped for the same sorts of battle. By French of German standards they weren’t cavalry at all; they were mounted infantry (or rifles), intended to move about quickly on horseback but to engage the enemy dismounted.
In the latter part of the South African War (1899 – 1902), the British were pestered by the Afrikaner ‘Mounted Shooters’ who used American cavalry tactics, and the British responded by training their own units to fight in this way, including the Canadian and New Zealand Mounted Rifles and the Australian Light Horse.
In 1914 the U.S. Army (excluding National Guard) numbered 98,544 men, making up twenty regiments of infantry and seventeen of cavalry. Compared to the European powers, this was a very small force. Even the British, whose army was also small by comparison to their neighbors, had thirty-one regiments of cavalry. After 1914 the U.S. Army began to raise more cavalry regiments, not in anticipation of joining the European War but for Mexican Border service; in 1917 two of these nascent formations were converted to artillery and one to infantry.
When the U.S. declared war against Germany there were thirteen U.S. Cavalry regiments engaged in either guarding the Mexican border or chasing Francisco ‘Pancho’ Villa around northern Mexico. Of the remaining four regiments, one was in the Philippines, one was in the Canal Zone, one was in Arizona keeping the peace in the Bisbee mines and one, the 2nd, was engaged in training two of the new regiments that were being raised by enlistment.
Although there were still some state cavalry units in 1917, during the reorganization of the National Guard these were all disbanded and their personnel transferred to other branches.
The planners of the American Expeditionary Force (AEF) envisioned a limited role for their cavalry, having observed that most European units had been dismounted to serve as infantry. Accordingly, the AEF asked for only four cavalry regiments, and were allocated the 2nd, the 3rd, the 6th and the 15th.
When then-Maj. Gen. Pershing and his advance party arrived in France in June 1917, his personal detail included 31 troopers from the 2nd Cavalry, but the first whole regiment to arrive in France was the 3rd Cavalry, in November 1917. They were pulled away from the Mexican Border and assigned to operate three newly-created horse remount depots in France. The three squadrons were charged with the purchase of horses, mules and forage, the care, conditioning, and training of mounts before issue, the reconditioning of sick or injured animals and their subsequent re- issue.
K Troop 3rd Cavalry was detached to serve as scouts, first in I Corps during the Aisne-Marne Offensive (18 July – 6 August 1918), and then served in III Corps on the Vesle Front (7-17 August), in the Oise-Aisne Offensive (18 August – 9 September), and the Meuse-Argonne Offensive (14 September – 11 November).
The 6th Cavalry, recently released from Mexican service, arrived in France in March 1918 and was first assigned to remount depots and later to military police duty rounding up stragglers in the Meuse Argonne Offensive.
The 2nd Cavalry was withdrawn from training and arrived in France in April 1918. They were also used to manage remount depots and as military police, but later Troops B, D, F, and H were formed into a provisional squadron, which served in the Aisne-Marne Offensive (18 July-6 August), and then in support of the 1st and 2nd Infantry Divisions at Soissons (18 – 22 July), before rejoining the regiment. Small detachments of the 2nd Cavalry then served in the Oise-Aisne Offensive (8 August-11 September).
In the Battle of Saint-Mihiel (12 – 16 September) Troops A, B, C, D, F, G, and H fought under the command of Lt. Col. O.P.M. Hazzard, and at Vieville Troop F staged the only horse-mounted charge by the AEF in the war.
With no rest, the 2nd Cavalry was moved to the Meuse-Argonne Offensive (26 September-11 November). From 26 September-2 October, spearheading the assault on the left flank, the 2nd fought a six-day running battle starting in Vauquois and winding through the woods nearby. The 2nd was cited for “…accomplishing their tasks with fearlessness, courage, and disregard for danger and hardship”.
Later the 2nd served with the main effort of the advance between the Meuse River and the Argonne Forest. You can read more about the 2nd Cavalry here.
Lastly, the 15th Cavalry was also withdrawn from Mexican Border service and arrived in France in May 1918. However, the regiment was disbanded and the troopers were reassigned as infantry replacements.
You can read more about the 2nd Cavalry here. Elements of all of these regiments are serving on active duty today as either armored or air cavalry.