Early in September, Lee dispatched two divisions of Lt. Gen. James Longstreet's Corps to reinforce the Confederate Army of Tennessee for the Battle of Chickamauga. Meade knew that Lee had been weakened by the departure of Longstreet and wanted to take advantage. Meade advanced his army to the Rappahannock River in August, and on September 13 he pushed strong columns forward to confront Lee along the Rapidan, occupying Culpeper, Virginia, following the Battle of Culpeper Court House. Meade planned to use his numerical superiority in a broad turning movement, similar to the one planned by Maj. Gen. Joseph Hooker in the Battle of Chancellorsville that spring. However, on September 24 the Union had to deplete its forces as well, sending the XI and XII Corps to the Chattanooga campaign in Tennessee.