The Battle of Mechanicsville, also known as the battle of Beaver Dam Creek. which opened the Confederate offensive of the Seven Days on June 26, 1862 was a tactical fiasco and defeat for the Army of Northern Virginia and a strategic defeat for the Army of the Potomac.
Lee’s plan to attack Porter’s V Corps, the only corps of the Army of the Potomac north of the Chickahominy, defeat it and turn the right flank of the Army of the Potomac went badly awry in execution. Beginning the poor performance that would plague him throughout the Seven Days, Jackson was four hours late in attacking the north flank of Porter’s corps. Instead, AP Hill attacked with his division in futile and bloody frontal assaults which were easily repulsed by Porter. After Jackson’s arrival, he bivouacked his men, although the sounds of a major attack were clear. AP Hill renewed his attacks, reinforced by DH. Hill’s brigade, although Lee had ordered no more attacks and was again bloodily repulsed. Confederate casualties were 1461 with Union casualties half this number. So a humiliating tactical defeat for the Confederates marked by an inept inability on the part of Lee to put forward a coordinated attack.
However, McClellan turned this day of Confederate defeat into one of victory. Assuming, as he always did, that he was heavily outnumbered, and fearing that Jackson was positioned to march into his rear and cut off his supply lines, McClellan ordered Porter to retreat, and decided to abandon his supply line which relied upon the rail line north of the Chickahominy, the York and Richmond Railroad, and to rely upon a supply line by water up the James River. This decision meant that he was going to have to withdraw from his positions in front of Richmond and retreat down the Peninsula. Few defeats have reaped such rich rewards as Mechanicsville did for the Confederacy. Here is General Lee’s report on the battle of Mechanicsville which was written on March 6, 1863: (more…)