his command worn out by the mistaken use of mounted men to protect trains — a duty which could be as well and much more economically performed by infantry; and by the unnecessary picket-duty, encircling the great infantry and cavalry camps of the Army of the Potomac on an irregular curve of nearly sixty miles. In October, 1862, when service in the Peninsula campaign and in that of the Army of Virginia, had brought the number of mounted cavalrymen down to less than a good-sized regiment, McClellan wrote Halleck:
It is absolutely necessary that some energetic measures be taken to supply the cavalry of this army with remount horses. The present rate of supply is 1,050 per week for the entire army here and in front of Washington. From this number the artillery draw for their batteries.The demand for horses was so great that in many cases they were sent on active service before recovering sufficiently from the fatigue incident to a long railway journey. In one case reported, horses were left on railroad cars fifty hours without food or water, and were then taken out, issued, and used for immediate service in the field. To such an extent had overwork and disease reduced the number of cavalry horses in the Army of the Potomac, that when the Confederate general, Stuart, made his daring raid into Pennsylvania, in October, 1862, only eight hundred Federal cavalrymen could be mounted to follow him. Of course the original mounting of the cavalry, field-artillery, and field-and staff-officers caused a great demand for suitable chargers throughout the North. The draft animals required for transportation purposes increased the scarcity of suitable horses. Furthermore, with the unexpected losses during the first years of the war came such a dearth of animals suitable for the cavalry service, that in course of time almost any remount which conformed to the general specifications of a horse, was thankfully accepted by the Government.