The 3rd MSM Cavalry Regiment (New) did not exist until February 1863. It was the organization of the 10th MSM Cavalry Regiment, a predecessor unit of the 3rd MSM Cavalry, that was perfected in May 1862. Prior May 1862, the 10th MSM Cavalry Regiment was the 10th MSM Cavalry Battalion. In May 1862 Morsey's Mounted Rifles Battalion was integrated into the 10th MSM Cavalry Battalion, creating the 10th MSM Cavalry Regiment. Companies A, B, and C of Morsey's Mounted Rifles became Companies F, G and H of the 10th MSM Cavalry Regiment. That summer, the Louisiana Red Rovers Independent Artillery Company, from Pike County, was integrated into the 10th MSM Cavalry Regiment, becoming Company I.

Starting in December 1861, politically-connected Unionists throughout Missouri jumped on the bandwagon en masse recruiting MSM units. The recruiting got so much out of hand that Congress put a stop to it by Spring 1862, capping the number of MSM enlistments at 10,000, resulting in the discharging of large numbers of recruits and consolidating a number of the more viable independent units that existed. Most of those consolidations took place in May 1862, including Morsey's independent battalion and the 10th MSM battalion.

From December 1861 to May 1862, Edwin Smart (retired from the 2nd U.S. Dragoons) and Bazel Lazear (postmaster of Ashley, Pike County) were recruiting in Pike County, Missouri; Pike County, Illinois; and Ralls County, Missouri for the 10th MSM Cavalry Battalion. During those same months, Freiherr (Baron) Frederick Morsey (Warren County landowner and attorney) was recruiting in Warren, Lincoln and Montgomery Counties. James Wilson was from Lincoln County, and thus was brought into the orbit of Morsey.

When Morsey's Mounted Rifles and the 10th MSM Cavalry Battalion were combined in May 1862 to form the 10th MSM Cavalry Regiment, Smart was made colonel, Morsey was made lieutenant colonel, and a short-shrifted and angry Lazear took his toys and went home. Through his political connections, Lazear afterwards found a position in the 12th MSM Cavalry in southeast Missouri. When that unit was disbanded in February 1863 and part of it was, coincidentally, integrated into the 10th MSM Cavalry Regiment, Lazear ended up in the 1st MSM Cavalry Regiment in western Missouri.

Histories of the 3rd MSM Cavalry Regiment (New) generally include actions that its predecessor units participated in, particularly those that took place in northeast Missouri in 1862 before the regiment received its 3rd MSM (New) designation. Histories (Dyers) also tend to incorrectly include southwest Missouri 1862 actions that involved the 3rd MSM Cavalry (Old) as having been undertaken by 3rd MSM Cavalry (New).

In any event, it was Morsey's Independent Battalion that was involved in actions against Henderson in early 1862 (the Pike County boys had their hands full further north). And, it would seem, these early-1862 actions by Freiherr Morsey's Warren, Lincoln and Montgomery County boys helped bring pre-war stone mason James Wilson to the notice of senior Missouri military officers, catapaulting him from enlisted man to field officer during this general time frame.