Hal,

At the beginning of the war in the Confederate Army it was policy for the individual to furnish his own horse. I don't believe the Union had that policy. Also it helped to be able to ride!. Contrary to popular conception not everyone was a rider in those days. The artillery, being the most technical of the branches, usually got the more adept personnel. By and large what dictated the placement of a soldier was the situation under which a unit was organized. Most units organized were infantry. This was the least expensive unit to equip and the need for infantry was greater. Many men of the time would not serve, especially in the Confederate Army, if they couldn't be Cavalry. It seemed to have something to do with having an aversion to walking! A case in point was the organization of the 22nd Va. Cavalry in 1863. It seems that the men said if they couldn't be cavalry they wouldn't serve! The Confederate War Dept. had already discontinued organizing cavalry units but so as not to lose the troops of the 22nd they allowed the group to be Cavalry. Hope this helps.

Len