On Saturday, August 10, 1861, Nathaniel Lyon led a Union command of only 4,200 men in the second battle of the Civil War, hoping a surprise attack on the Southern encampment below the hill would end the Southern army's advance toward Springfield, drive the Southerners into Sigel, damage the enemy, and keep Missouri in the Union. Although Lyon's men were better armed and equipped, they were too few, and the Southern army's unexpectedly stiff resistance, combined with the weight of twice their number, stalled the Union advance and forced it onto the defensive. Taking advantage of the high ground and shifting their positions to meet Southern threats, Union soldiers fought valiantly for five hours and lost a quarter of their number. The battle was fought on these grassy slopes dotted with oak trees, and the first Union general killed in combat died here.