The division was inactivated on 12 May 1918 and its remaining units sent back to the border as replacement National Army regiments were considered insufficiently trained.
The organization of the division was ordered by the United States War Department on 27 November 1917 from the nine Regular Army cavalry regiments guarding the Mexico–United States border, in response to the desire of American Expeditionary Forces (AEF) commander on the Western Front General John J. Pershing for a mobile cavalry reserve despite French and British suggestions against establishing such a unit.
[2][3] The three cavalry brigades were authorized 14,268 combatants and non-combatants, out of the total division strength (including support units) of 18,176.
[4] The Commanding General of the Southern Department, Major General Willard Ames Holbrook, proposed that the division be broken up on 6 May 1918, as he considered the National Army regiments insufficiently trained to be able to replace the Regulars within nine months, and the divisional organization unwieldy for border patrol duty.
[2] Pershing was informed by Secretary of War Newton D. Baker that all remaining cavalrymen were required for border duty, ending the possibility of employing a cavalry division on the Western Front.