Cheatham's artillery bombardment began at 12:30 p.m., but he did not immediately order his infantry forward. Union troops continued to file into line, extending their flank to the north, beyond the intended avenue of attack. Bragg moved Cheatham's division into Walker's Bend, assuming the redirected attack would now strike the Union's open flank. Unfortunately for the Confederates, their cavalry reconnaissance withdrew before McCook placed an artillery battery under Lt. Charles Parsons and the brigade of Brig. Gen. William R. Terrill onto the Open Knob, a prominent hill on the northern end of the battlefield.