The 15th Cavalry Division was created with the 1st & 2nd Cavalry Brigades in February 1917 at Fort Sam Houston, Texas. It numbered in succession of the 1st–14th Divisions, which were not all active at its creation. Originally trained for deployment to Europe, its units were later converted into field artillery units. The division was deactivated on 12 May 1918. Elements of the division were reconstituted as the 1st Cavalry Division in 1920.
Headquarters Element (34 men)
1st Cavalry Brigade (2,803 men)
3rd Cavalry Regiment
14th Cavalry Regiment
15th Cavalry Regiment
2nd Cavalry Brigade (2,803 men)
Battery C, 6th Field Artillery (Horse)
5th Cavalry Regiment (Transferred from Fort Bliss, Texas to Camp Stewart, Texas in April 1917).
8th Cavalry Regiment (Transferred from Philippines Department to Fort Bliss, Texas in April 1917)
9th Cavalry Regiment (Assigned to Fort Bliss, Texas; patrolled the US-Mexican Border from 1912 to 1917. Transferred from Fort Bliss, Texas to Philippines Department in April 1917)
10th Cavalry Regiment (Assigned to Fort Huachuca, Arizona; patrolled the US-Mexican Border from 1913 to 1933).
17th Cavalry Regiment (Raised 1916; Assigned to Fort Bliss, Texas in April 1917)
3rd Cavalry Brigade (2,803 men)
12th Cavalry Regiment
13th Cavalry Regiment
7th Field Artillery (790 men)
Engineer Battalion (357 men)
Division Quartermaster Trains Command (276 men)
Special Troops Command (337 men)
Field Hospital No. 7
Ambulance Company No.7 (63 men)
Headquarters, 15th Cavalry Division was located at Fort Bliss, Texas
1st Cavalry Brigade at Fort Sam Houston, Texas
2nd Cavalry Brigade at Fort Bliss
3rd Cavalry Brigade at Fort Riley, Kansas, later Douglas, Arizona.
During World War One the National Guard organized four cavalry divisions: the 21st, 22nd, 23rd, and 24th. The Organized Reserves organized six Cavalry Divisions: the 61st, 62nd, 63rd, 64th, 65th, and 66th.
15th Sustainment Brigade derives its numerical designation from its origin as the 15th Cavalry Division Quartermaster Trains.
The brigade support battalions of the 1st Cavalry Division derive their numerical designations & lineage from the 15th Quartermaster Squadron & 15th Medical Squadron.
