Hooker's plan for the spring and summer campaign was both elegant and promising. He first planned to send his cavalry corps deep into the enemy's rear, disrupting supply lines and distracting him from the main attack. He would pin down Robert E. Lee's much smaller army at Fredericksburg, while taking the large bulk of the Army of the Potomac on a flanking march to strike Lee in his rear. Defeating Lee, he could move on to seize Richmond. Unfortunately for Hooker and the Union, the execution of his plan did not match the elegance of the plan itself. The cavalry raid was conducted cautiously by its commander, Brig. Gen. George Stoneman, and met none of its objectives. The flanking march went well enough, achieving strategic surprise, but when he attempted to advance with three columns, Stonewall Jackson's surprise attack on May 1 pushed Hooker back and caused him to withdraw his troops. From there, Hooker pulled his army back to Chancellorsville and waited for Lee to attack. Lee audaciously split his smaller army in two to deal with both parts of Hooker's army. Then, he split again, sending Stonewall Jackson's corps on its own flanking march, striking Hooker's exposed right flank and routing the Union XI Corps. The Army of the Potomac dropped into a purely defensive mode and eventually was forced to retreat.