On May 1, 1863, the head of Union Gen. Joseph Hooker’s Army of the Potomac arrived on these fields after completing an elaborate maneuver in which a column that eventually numbered 80,000 men crossed two rivers, pushed through the Wilderness of Spotsylvania County, and stood ready to descend on the left flank and rear of Confederate Gen. Robert E. Lee’s Army of Northern Virginia, posted on the Rappahannock River above and below Fredericksburg. Momentarily deceived by the 30,000 Union troops left opposite Fredericksburg, Lee was slow to respond, but on April 30 reports from scouts and other units on the Rappahannock confirmed Hooker’s sweeping flank movement. Lee then moved quickly to blunt the advance, leaving 10,000 soldiers at Fredericksburg while Lee and Thomas J. “Stonewall” Jackson marched with 42,000 men to confront Hooker’s main force, and the columns collided here on the open fields on May 1.