The rules of strategy are few and simple.  They may be learned in a week.  They may be taught by familiar illustrations or a dozen diagrams.  But such knowledge will no more teach a man to lead an army like Napoleon than a knowledge of grammar will teach him to write like Gibbon.  Lincoln, when the army he had so zealously toiled to organise, reeled back in confusion from Virginia, set himself to learn the art of war.  He collected, says his biographer, a great library of military books; and, if it were not pathetic, it would be almost ludicrous, to read of the great President, in the midst of his absorbing labours and his ever-growing anxieties, poring night after night, when his capital was asleep, over the pages of Jomini and Clausewitz.  And what was the result?  In 1864, when Grant was appointed to the command of the Union armies, he said:  “I neither ask nor desire to know anything of your plans.  Take the responsibility and act, and call on me for assistance.”  He had learned at last that no man is a born strategist.

The mistakes of Lincoln and Stanton are not to be condoned by pointing to McClellan.

McClellan designed the plan for the invasion of Virginia, and the plan failed.  But this is not to say that the plan was in itself a bad one.  Nine times out of ten it would have succeeded.  In many respects it was admirable.  It did away with a long line of land communications, passing through a hostile country.  It brought the naval power of the Federals into combination with the military.  It secured two great waterways, the York and the James, by which the army could be easily supplied, which required no guards, and by which heavy ordnance could be brought up to bombard the fortifications of Richmond.  But it had one flaw.  It left Washington, in the opinion of the President and of the nation, insecure; and this flaw, which would have escaped the notice of an ordinary enemy, was at once detected by Lee and Jackson.  Moreover, had McClellan been left in control of the whole theatre of war, Jackson’s manoeuvres would probably have failed to produce so decisive an effect.  The fight at Kernstown would not have induced McClellan to strike 40,000 men off the strength of the invading army.  He had not been deceived when Jackson threatened Harper’s Ferry at the end of May.  The reinforcements sent from Richmond after Port Republic had not blinded him, nor did he for a moment believe that Washington was in actual danger.  There is this, however, to be said:  had McClellan been in sole command, public opinion, alarmed for Washington, would have possibly compelled him to do exactly what Lincoln did, and to retain nearly half the army on the Potomac.