It was intolerably provoking, unintelligible, and ridiculous that a ragged, ill-shod, overworked, under-fed, and beaten body of Southerners should be able to retreat faster than a great, fresh, well-fed, well-equipped, and victorious body of Northerners could follow. Jackson said that the Northern armies were, kept in too good condition; and declared that he could whip any army which marched with herds of cattle behind it. But the North preferred, and justly, to attribute the inefficiency of their troops to the unfortunate temperament of the commander. Mr. Lincoln looked at the unsatisfactory spectacle and held his hand as long as he could, dreading perhaps again to seem too forward in assuming control of military affairs. Patience, however, could not endure forever, nor common sense be always subservient to technical science. Accordingly, on October 6, he ordered McClellan to cross the Potomac, and either to "give battle to the enemy, or to drive him south." McClellan paid no attention to the order. Four days later the Confederate general, Stuart, with 2000 cavalry and a battery, crossed into Maryland and made a tour around the Northern army, with the same insolent success which had attended his like enterprise on the Peninsula. On October 13 the President wrote to McClellan a letter, so admirable both in temper and in the soundness of its suggestions that it should be given entire:-- "MY DEAR SIR,--You remember my speaking to you of what I called your over-cautiousness. Are you not over-cautious when you assume that you cannot do what the enemy is constantly doing? Should you not claim to be at least his equal in prowess, and act upon the claim? "As I understand, you telegraphed General Halleck that you cannot subsist your army at Winchester, unless the railroad from Harper's Ferry to that point be put in working order. But the enemy does now subsist his army at Winchester at a distance nearly twice as great from railroad transportation as you would have to do without the railroad last named. He now wagons from Culpepper Court House, which is just about twice as far as you would have to do from Harper's Ferry. He is certainly not more than half as well provided with wagons as you are. I certainly should be pleased for you to have the advantage of the railroad from Harper's Ferry to Winchester; but it wastes all the remainder of autumn to give it to you, and, in fact, ignores the question of _time_, which cannot and must not be ignored.