Many thanks for the detailed information. For those interested in this topic, I have also found three supplemental sources to be of value: 1. Journal of Assistant Surgeon Thomas Fanning Wood (3rd North Carolina) on the medical organization within a regiment; 2. An account of the ordnance organization by Colonel William Allan, Chief of Ordnance in Ewell's Second Corps; and 3. Thomas Livermore's (5th New Hampshire) description of the ambulance trains in the Union Second Corps, which had just over 100 ambulances with 300 horses run by 13 officers and 350-400 men. These enormous wagon trains explain why BGen Imboden indicated that the 1000-1200 wagons guarded by his command during Lee's retreat from Gettysburg stretched for 17 miles - or just under 20 miles according to one of his soldiers. An assortment of vehicles and the horses to pull them were also "requisitioned" from the citizens of southern Pennsylvania and added to the official total, plus the 175 wagons pulled by 900 mules that Stuart captured just outside of Washington and which fatally delayed his arrival to Gettysburg. However, offsetting the captures, during the retreat harassing Union cavalry broke into the Confederate trains and captured or destroyed at least 200 wagons. Significant manpower (perhaps 6 percent?) was dedicated from the ranks of each regiment to provide drivers for these vehicles. Imboden mobilized 700 wagoners alone for his successful defense of his train at Williamsport, Maryland, arming them with captured weapons, but that's another story.