On August 9, 1861, Lyon marched his troops from Springfield to where the Confederates were now camped at Wilson Creek. His plan called for Colonel Sigel to do a flanking maneuver on the Confederates and attack them from their rear. The rest of Lyon's forces would attack from the north. On August 10, the (first) Battle of Wilson's Creek began with Sigel's flanking maneuver which surprised the Confederate army. It allowed the Union army an early advantage. The two armies fought fiercely in the fields and hills around Wilson's Creek. After six hours of fighting and numerous casualties on both sides, the Union forces withdrew. During the battle, Lyon was killed and Major Sturgis replaced him. Three times the confederates attacked the Union line and failed to break through all three times. After the third attack at about 11:00 am, the Confederates fell back. With his ammunition running low and his men exhausted Sturgis withdrew to Springfield. Too disorganized to follow, the Confederate army did not pursue. While it was a technical victory for the Confederates, the Union army kept control of Missouri for the rest of the war.