Evelyn, I think Anthony Rushing can do a better job of discussing the pre-Civil War militia than I can, but, briefly, the Arkansas State Militia was, for want of a better analogy, the "National Guard" of its time. All able-bodied men of military age were expected to be members of a local militia company, subject to the call of the Governor in case of civil unrest or military invasion.
Regiments were organized on a county basis. Companies seem to have been organized on a township basis. Officer appointments were subject to the approval of the Governor.
As far as I can tell, there were no weekend drills, but the county militia regiments were supposed to muster once a year (usually in late winter or early spring) for inspection and drill. There isn't much evidence that many of the militia regiments held an annual muster, but local newspaper accounts indicate that some regiments did, and these annual musters appear to have been an occasion for social activities, as well as military drill.
With one exception, none of the prewar militia regiments were called to duty during the war. Most of the militia members joined the Arkansas State Troops or Confederate volunteer regiments. Only the 45th Militia Regiment, of Searcy County, performed any duty -- they were involved in rounding up suspected members of the so-called Peace Society in November and December 1861. I ran across some correspondence requesting that the 7th Militia Regiment, of Pulaski County, be ordered to duty, but virtually all the members of the regiment were currently in Confederate service, so, like most of the other militia regiments across the State, existed only on paper.
George A. Davis had been a member of the 8th Militia Regiment, of Hempstead County, before the war. He later raised a company of cavalry in Hempstead County, of which he was elected captain. The company was assigned to Monroe's Regiment as Co. C.