The battle that climaxed the major Confederate invasion of Kentucky was fought on the hills west of Perryville. A sharp clash occurred on October 7 to gain possession of the only water supply in the vicinity, and the opposing armies took positions along a north-south battle line three miles long. At the northern end of that line, at 2 o'clock on the afternoon of October 8, 1862, a fierce charge by General John A. Wharton's cavalry on the Confederate right wing marked the beginning of the battle. After the cavalry opened the way, the entire Confederate right wing charged up the hill against the Union extreme left wing. Confederate casualties were heavy as the attackers crossed a rail fence into an open field under heavy fire from Lieutenant Charles C. Parson's battery of eight guns on the hill, but the charge forced the Union troops to retreat. As fighting became general along the entire line, the advantage by nightfall seemed to favor the Confederates. Of the 16,000 Confederates engaged, 1,822 casualties were sustained, while the Federals, who had used only 22,000 of their 61,000 men, sustained 4,241 losses. General Buell expected the battle to resume the next morning, but General Bragg, realizing he was greatly outnumbered, began a midnight retreat to Harrodsburg. After waiting four days to reorganize, the Union army pursued Bragg but allowed the Confederate army to escape and finally withdraw from Kentucky into Tennessee through Cumberland Gap, ending the major Confederate invasion of Kentucky.