On April 27, 1863, once his army is ready, Hooker secretly sends out the V, XI, and XII Corps on a march around Lee's left flank, bound for the exposed Confederate rear. For the first 36 hours, Lee is completely unaware of what is happening just across the Rappahannock. At the same time, Hooker initiates the other part of his plan and sends Sedgwick's VI Corps across the river just south of Fredericksburg. It is not until May 30 that the Confederate general gets the first reports of a federal column marching into his rear. Unsure of its size or intention, Lee leaves a small force to hold Sedgwick and sends Jackson with the rest of his Second Corps west against this unknown column. The next day, the two forces will come to blows in the dense woods of the Virginia Wilderness, near the forest manor of Chancellorsville.