Prelude to the Battle
Within twenty-four hours of the Union’s defeat at the First Battle of Bull Run (July 21, 1861), the Lincoln administration called upon George B. McClellan to lead the Union war effort in the East. McClellan spent the first few months of his new command fortifying Washington, DC, and reorganizing federal forces. The Northern public and politicians, however, wanted action. Accordingly, McClellan devised plans for an offensive to capture the Confederate capital at Richmond, Virginia to bring a quick conclusion to the war.
Although President Abraham Lincoln favored an overland assault on Richmond from the Washington area, McClellan developed a more complex strategy. Correctly believing that Confederate leaders expected a direct onslaught against the Confederate capital, McClellan proposed to outmaneuver the Rebel army guarding Richmond and to launch an offensive from the southeast, up the Virginia Peninsula.
The Virginia Peninsula is a strip of land in southeastern Virginia that runs from the northwest to the southeast. It is bordered on the north and east by the York River and on the south and west by the James River. Although nearly the entire area was behind Confederate lines early in the war, the Union maintained possession of Fort Monroe at the very tip of the peninsula.
McClellan planned to use the Union’s superior naval resources to transport the Army of the Potomac down the Chesapeake Bay, to disembark at Fort Monroe, and then to move up the peninsula, attacking Richmond from the rear. In early March, the Confederate Navy launched the ironclad CSS Virginia, posing a menace to federal control of the waters around Fort Monroe. Virginia’s launch threatened the success of McClellan’s plan. The appearance of the USS Monitor at the Battle of Hampton Roads forced Virginia’s withdrawal on March 9 and erased the Confederate threat.
McClellan’s offensive began on March 17, when he began transporting his army of approximately 120,000 men to Fort Monroe. McClellan arrived on site on April 2, and two days later, the Army of the Potomac began its advance up the peninsula toward Yorktown.
Confederate officials had prepared for McClellan’s offensive. In 1861, Major General John Bankhead Magruder, commander of the Army of the Peninsula, began constructing defensive lines across the Virginia Peninsula. The mainline, known as the Warwick Line, connected Yorktown on the York River to the headwaters of the Warwick River and then extended southwest to the confluence of the Warwick and James Rivers.
McClellan Orders a Siege
As McClellan’s men began their advance up the peninsula on April 4, they soon encountered Rebel skirmishers who quickly fell back to the Warwick Line. Magruder had only 12,000 soldiers at his disposal to defend the line, which stretched for approximately twelve miles across the peninsula. When McClellan’s immense army could have overrun the Rebel defenses, Magruder’s creativity made up for his lack of manpower. As McClellan’s scouts watched, Magruder skillfully moved his men about, behind his defenses, creating the illusion that his force was much larger than it really was. The charade deceived McClellan into estimating the size of Magruder’s army to be over 40,000 soldiers. Magruder’s theatrics, combined with McClellan’s tentative nature, prompted the Union general to order his men to entrench and to prepare for a siege, rather than to overwhelm their adversaries.
As McClellan’s army dug in and constructed siege fortifications, Confederate officials began shifting soldiers from northern Virginia to the Virginia Peninsula. By late April, Confederate leaders merged the Army of the Peninsula into the Right Wing of the Army of Northern Virginia and General Joseph E. Johnston arrived to take command of the 56,000 troops that now stood between McClellan and Richmond.
Battle of Dam No. 1
During the four-week siege, McClellan made one major attempt to break the Confederate line. On April 16, Union forces, commanded by Brigadier General William F. “Baldy” Smith, crossed the Warwick River to test the Confederate defenses near Dam No. 1, where Union Brigadier General Winfield S. Hancock had reported a potential vulnerability. McClellan’s orders to avoid a general engagement hampered Smith. Yankee soldiers pushed the enemy back until a Rebel counterattack drove Smith’s men back across the bridge, thus ending the only real Federal attempt to breach the Rebel defenses during the siege.
For the next two weeks, McClellan continued to amass siege artillery in front of the Warwick Line, while trying unsuccessfully to convince the navy to outflank the Rebels by moving flotillas up the York and James Rivers. By April 22, Johnston realized that his defenders had no chance of withstanding the looming barrage from McClellan’s artillery, which eventually totaled 101 siege guns. Consequently, Johnston recommended withdrawing his forces to new defensive lines closer to Richmond. However, Confederate President Jefferson Davis, heeding the advice of his military adviser Robert E. Lee, ordered Johnston to remain in his current position. Finally, as McClellan made his final preparations to unleash the full might of his artillery, Johnston’s views prevailed. On the night of May 3, Johnston ordered a covering artillery barrage of his own, as his troops and supply trains began falling back toward Richmond. The next morning, Union Major General Samuel P. Heintzelman boarded an observation balloon, ascended over the Confederate defenses, and reported to a stunned McClellan that the Rebels had vanished during the night.
Aftermath of the Battle
Because McClellan’s army held the field after forcing the Rebel defenders to abandon the Warwick Line, the Siege of Yorktown was tactically a federal victory. In addition, the Union suffered only 182 casualties compared to 300 for the Confederacy. Still, the month-long delay enabled the Rebels to strengthen their defenses and to concentrate enough forces south of Richmond to protect the Confederate capital and, ultimately, to derail McClellan’s Peninsula Campaign.