The "Mobile Dragoons" enrolled for twelve months under Capt. James Hagan at Mobile, Ala., July 30, 1861, the original muster roll being dated Aug. 2, 1861. Officers and men reenlisted for two years or the war on May 19, 1862, serving as an independent command stationed at Bayou LeBatre, Ala. In early summer of 1863, it was designated Company "B", Murphy's Florida-Alabama Cavalry Battalion.
The 15th Confederate Cavalry Regiment organized at Hall’s Mills, Ala., Sept. 12, 1863. The Adjutant and Inspector General recognized this command on Sept. 24, 1863. Its components were four companies of the 3rd Florida Cavalry Battalion, four companies from Murphy’s Alabama-Florida Cavalry Battalion, and two independent cavalry companies.
Members of the "Mobile Dragoons" included men from Mobile and other southern counties of Alabama and Mississippi, as well as a contingent from New Orleans.
Contemporary Alabama newspapers would be a useful source for this kind of information. Here's an example from the Clarke County (AL) Journal, April 16, 1863 (Vol. VIII, No. 06).
NEWS OF THE WEEK
400 of the enemy, and mostly “contraband” troops, landed at Pascagoula last Thursday under cover of two gunboats. They were attacked by Captain John Marshall’s company of mounted men, and repulsed with a loss of 15 killed. Lieut. Hill and one private of the Confederates, slightly wounded. One gunboat, the Gen. Banks, put back to Ship Island with the wounded, and the others were still lying three quarters of a mile from the shore. Major Boyles, with his battalion of partisan rangers and a battery of artillery, has gone to the scene of action.