The struggle for Missouri erupts with the Battle of Wilson's Creek, where a motley band of raw Confederates defeat a Union force in the southwestern section of the state.
Union General Nathaniel Lyon, who commanded a force of 6,400 soldiers near Springfield, Missouri, was up against two Rebel forces commanded by Generals Sterling Price and Ben McCulloch. Although the Confederates were poorly equipped and trained at this early stage of the war, Price and McCulloch had a combined force nearly twice the size of Lyon's. But the impetuous Union commander did not want to cede the region without a fight, and so he planned an attack on August 10.
Lyon sent General Franz Sigel with 1,200 men to attack the rear while he struck the surprised Confederates just after dawn. At first, the artillery barrage sent the Rebel camp into a panic, and the day seemed to belong to the Yankees. But Sigel mistook a force emerging from the smoke for an Iowa regiment, when it was actually a Louisiana regiment clad in similar uniforms since many of the Rebel units were dressed in colors of their own choosing. The Confederates pushed Sigel back, and the tide turned against Lyon's force as well. In intense heat and humidity, the armies battled throughout the morning. Lyon was killed during one of the Confederate assaults, but the Union line managed to hold their ground. Although the Rebels withdrew from the field, the Union army was disorganized and running low on ammunition. Losses were heavy, with both sides suffering about 1,200 casualties. The Federals soon retreated to Springfield and then back to the railhead at Rolla, Missouri, 100 miles to the northeast. Southwestern Missouri was secured for the Confederates.