I do think that the logistic tail in fact might have been quite considerable... transportation is a part of it and here is part of the report Quartermaster-General M. C. MEIGS handed to the secretary of war on November 18, 1862
In our armies the requisitions for transportation have been enormous. The Army of the Potomac in July, at Harrison's Landing, when less than 100,000 strong, after its losses in the retreat to the James River, had 2,578 wagons and 415 ambulances, drawn by 5,899 homes and 8,708 mules--14,607 animals employed in the trains. In addition to these there were 12,378 cavalry and artillery horses, making 26,985 homes and mules to be fed. The supply of these animals with forage, almost entirely shipped from the Northern ports, was very costly. The position of the army did not allow of more than a few days' supply being landed at any time, and the vessels in which it had been shipped were kept in some cases for months on demurrage at enormous expense.
This same army was moved to Washington, re-enforced, and marching to Sharpsburg, fought the battles of South Mountain, Crampton's Gap, and Antietam, and lay for some weeks along the Upper Potomac. On the 31st of October, from reports in this office, its nominal strength was 176,000, but so many men were absent sick, prisoners, or absent on leave that its effective strength is supposed not to have exceeded 130,000. It had with it 3,798 wagons, drawn by 19,558 animals, of which 7,673 were horses and 11,885 mules.