As Terry Justice pointed out in his post, the 15th MO Cavalry was created from the 7th Provisional Enrolled Missouri Militia. Enlistment papers show 15th MO CAV enlistments beginning as early as November 1, 1863, but the designation 15th MO CAV was not used until November 28, 1864. This situation is confusing to say the least.

If you are interested in the details of the 7th PEMM/15th MO CAV transition, I have a website on selected companies which gives the details that pretty much apply to all companies: