Milroy's advance and a Confederate scouting party had skirmished on December 12. The next morning, Milroy divided his troops into a two pronged attack to flank the Confederate camp. The first column advanced up the Staunton-Parkersburg Pike, engaging the Confederate right side for several hours before withdrawing. Because of the difficult mountain terrain, the second Union column arrived shortly after the withdrawal of the first column, therefore unable to support the main body of Union troops on the right as planned, but then attacked the Confederate left. When the left column of Union forces arrived, an officer believed that they were his own pickets returning, ordered his men not to fire and rode forth to bring them into the camp. The Confederate officer was killed by a shot from the Union troops, and the second part of the battle commenced with fierce fighting. After the right Union column had withdrawn, Johnson ordered all his troops who had been fighting there to join the battle on the left flank, and the concentrated Confederate fire broke up the left Union assault and the final Union troops withdrew.