After spending the winter of 1861-1862 preparing his Army of the Potomac, all the while being prodded by Lincoln to advance on the rebels, General George B. McClellan finally agreed to take action. Lincoln had wanted McClellan to attack Joseph Johnston’s Confederate army at Centreville and then push straight on through to Richmond. McClellan resisted, claiming that the Rebel defenses at Centreville were too stout and that an assault would merely be a disastrous repeat of Bull Run. McClellan presented an alternative plan that involved shipping troops down to Fort Monroe, at the tip of the Virginia Peninsula, and then speeding the army up the Peninsula to attack Richmond from the southeast, behind Johnston’s lines. Lincoln feared that this was simply another McClellan delay, and he directly ordered the general to probe the rebel defenses at Centreville. To Lincoln’s dismay and McClellan’s embarrassment, Johnston had already evacuated his army to Richmond, and the fortifications left behind indicated that the Confederate position had never been as large or imposing as McClellan had claimed. Artillery emplacements were discovered to contain “Quaker guns”—logs painted black to resemble cannons—and “there had clearly been no more than 45,000 rebels on the Manassas-Centreville line, fewer than half the number McClellan had estimated.”
Johnston’s retreat to Richmond negated McClellan’s plan to come in behind him up the Peninsula, but McClellan continued to press for this option. Lincoln was skeptical, and insisted that McClellan would “find the same enemy, and the same, or equal intrenchments” whether he attacked up the Virginia Peninsula or overland from Washington. Lincoln was also concerned that the Peninsula plan would leave Washington undefended should Johnston decide to make a move in that direction, and though the president “did not quite share [the abolitionists’] darkest suspicions” that such a move was deliberate on McClellan’s part, “he did find the matter troubling.” McClellan promised to leave enough troops behind to defend Washington, though Lincoln detached more soldiers than McClellan had wanted, and the Army of the Potomac embarked for Hampton Roads, Virginia.
In early April 1862, McClellan pushed up the Peninsula from Fort Monroe and approached Yorktown, where Confederate General John B. Magruder and thirteen thousand rebel soldiers hunkered down behind extensive defensive lines. McClellan was convinced that Magruder had far more troops than he actually had and that the fortifications would make a frontal assault far too costly. McClellan opted to besiege Yorktown and spent nearly a month preparing trenches and bringing up heavy guns with which to pound the rebel defenses. Lincoln was irritated by this delay, but McClellan insisted that it was necessary, writing “to his wife that if Lincoln wanted to break the rebel lines, ‘he had better come & do it himself.’” While the Army of the Potomac toiled in the expanding trenches around Yorktown, Johnston exploited the delay and moved his entire army to the Peninsula. Finally, on the night of May 3-4, and just as McClellan was ready to begin his bombardment, the Confederates evacuated Yorktown and headed back up the Peninsula. Jefferson Davis was angry with Johnston over this surrendering of territory, but no more so than Lincoln was with McClellan for the delay that allowed so many rebel troops to escape and prepare defenses farther up the Peninsula and closer to Richmond.
McClellan pursued the fleeing Confederate army, and by May, his “army of 100,000 had advanced to within hearing of Richmond’s church bells.” Confederate morale was understandably low, and Jefferson Davis pleaded with Johnston to attack McClellan’s army while McClellan dawdled outside Richmond. Johnston finally acted on May 31, and the indecisive Battle of Seven Pines inflicted a combined eleven thousand casualties on the two armies, including Johnston himself. General Robert E. Lee was selected by Davis to command Johnston’s Army of Northern Virginia, and the “quiet Virginian” quickly began to take the offensive. In a series of engagements known as the Seven Days’ Battles, Lee pushed McClellan and his army south to Harrison’s Landing on the James River. The Army of Northern Virginia was ably assisted in this endeavor by Jeb Stuart’s excellent cavalry and reinforced by Stonewall Jackson’s Shenandoah Valley army. Despite the fact that the Army of the Potomac more than held its own against the Confederates during much of the fighting, McClellan continued to issue orders to withdraw, prompting General Phil Kearny to remark, “Such an order can only be prompted by cowardice or treason…We ought instead of retreating to follow up the enemy and take Richmond.” McClellan wanted to remain at Harrison’s Landing, but because of mounting disease casualties in the hot and humid swamps, Lincoln ordered McClellan to evacuate in July 1862.
Whether McClellan’s caution was attributable to the prudence of a wise commander or, as some radical Republicans suggested, to sympathy with the Confederate cause, it is nonetheless clear that the commander of the Army of the Potomac allowed numerous opportunities to pass by him. Russel Beatie is obviously an admirer of McClellan’s, and his conclusion was that the Peninsula Campaign failed because of Lincoln’s micromanaging and unwarranted intrusions into day-to-day operations. There is no doubt some truth to Beatie’s assessment, but his defense of McClellan often feels like an armchair general’s after-the-fact rationalization, full of unnecessarily inflammatory accusations directed toward Lincoln and his administration and endless excuses for McClellan’s obvious failures. Had McClellan attacked overland to Centreville when Lincoln wanted him to, it is quite possible that the Army of the Potomac would have succeeded in smashing through defenses that were not as formidable as McClellan estimated them to be. At Yorktown, McClellan, in keeping with the standard doctrinal admonition never to leave the enemy in your rear, chose not to bypass Magruder and instead undertook a time-wasting siege. McClellan could have left a sizeable force capable of hemming Magruder in and keeping reinforcements out while navy gunboats bottled up the York River approaches. Thus free to resume his campaign, McClellan could have raced up the Peninsula and arrived at Richmond before Johnston had a chance to fully strengthen his positions and the city’s defenses. Once at Richmond, McClellan could have quickly assessed the situation and formulated a plan to assault the city, but he once again insisted on a siege. When Lee assumed command, he at once went on the offensive and pushed the Army of the Potomac back down to the James River and eventually back to Washington. McClellan was understandably worried about excessive casualties, in part because he had a habit of vastly overestimating his enemy’s strength of numbers. But as Stonewall Jackson was proving in the Shenandoah Valley, speed of maneuver could often negate numerical superiority, and even if McClellan’s army was outnumbered (which it was not), his constant delays did nothing but allow the Confederates to reinforce their troop strength and prepare their physical defenses. In the end, McClellan himself, whether through prudential caution or treasonous delay, was the reason the Peninsula Campaign failed.
 Allen C. Guelzo, Lincoln’s Emancipation Proclamation: The End of Slavery in America (New York: Simon & Schuster, 2004), 112-3.
 James M. McPherson, Battle Cry of Freedom: The Civil War Era (New York: Oxford University Press, 1988), 424.
 Lincoln quoted in McPherson, Battle Cry of Freedom, 424.
 Steven E. Woodworth, This Great Struggle: America’s Civil War (Lanham, MD: Rowman & Littlefield, 2011), 104.
 McPherson, Battle Cry of Freedom, 424-5.
 Quoted in ibid., 470.