Just to add to Richard Holloway's post, the records of soldiers I have seen and studied, principally from Virginia infantry regiments, shows detail periods of short duration -- a few days to a couple of weeks, but also details as teamsters for an extended period -- several months to a year or more, especially if the detail was to organizations in the Army of Northern Virginia like the Reserve Ordnance Train, or the Second Corps field hospital. These detailed men were paid an additional daily amount, $.25 if I recall correctly, above their normal salaries. I have also come across references to men, civilians, who were contacted to be teamsters. The references to such contractors are fewer than those of detailed military men. Finally, a significant number of teamsters were African Americans hired out by men serving in the Army. I certainly know of at least one instance where the teamsters of Lee's considerable wagon train fought in large numbers and with some determination and success. That occurred at the battle of Williamsport on July 6, 1863, when two divisions of Union cavalry attacked Lee's wagon train, which had been prevented from crossing the Potomac by high water. While the teamsters and drivers were not the only Confederate defenders among the scratch force commanded by John D. Imboden, the contribution made by the teamsters to the battle was apparently recognized by Imboden who reportedly called the battle "the wagoner's fight." There is a good account of this battle in "Retreat from Gettysburg," by Kent Masterson Brown. Brown's book also provides some perspective on the extent to which African Americans served as teamsters.