Early on the morning of May 2, Hooker began to realize that Lee's actions on May 1 had not been constrained by the threat of Sedgwick's force at Fredericksburg, so no further deception was needed on that front. He decided to summon the I Corps of Maj. Gen. John F. Reynolds to reinforce his lines at Chancellorsville. His intent was that Reynolds would form up to the right of the XI Corps and anchor the Union right flank on the Rapidan River.^[6]

Given the communications chaos of May 1, Hooker was under the mistaken impression that Sedgwick had withdrawn back across the Rappahannock and, based on this, that the VI Corps should remain on the north bank of the river across from the town, where it could protect the army's supplies and supply line. In fact, both Reynolds and Sedgwick were still west of the Rappahannock, south of the town.^[6]

Hooker sent his orders at 1:55 a.m., expecting that Reynolds would be able to start marching before daylight, but problems with his telegraph communications delayed the order to Fredericksburg until just before sunrise. Reynolds was forced to make a risky daylight march. By the afternoon of May 2, when Hooker expected him to be digging in on the Union right at Chancellorsville, Reynolds was still marching to the Rappahannock.^[6]