After a lengthy interlude with little military activity, McClellan marched his army across the Potomac River starting on October 26. On November 7, Lincoln replaced McClellan with Burnside. On November 15, Burnside began moving his army south towards Fredericksburg, Virginia, midway between the opposing capitals. On November 18, Longstreet began marching his men out of army headquarters in Culpeper towards Fredericksburg, where the Confederate army would make its stand against Burnside. Since Lee moved Longstreet to Fredericksburg early, it allowed Longstreet to build strong defenses. Longstreet ordered trenches, abatis, and fieldworks to be constructed south of the town along a stone wall at the foot of Marye's Heights. After a lengthy delay while waiting for the arrival of supplies to build pontoon bridges, Burnside attempted to cross the Rappahannock on December 11. Soldiers attempting to lay pontoon bridges encountered fierce resistance from Confederate troops inside of Fredericksburg, led by William Barksdale's brigade of McLaws' division. Burnside subsequently ordered an artillery bombardment of the town, and by the following day had moved his army across and occupied Fredericksburg. December 12 saw only a small amount of desultory fighting.