On August 10, 1861, the Union Army fought its first major engagement west of the Mississippi — and lost. The Battle of Wilson's Creek, fought in the hills south of Springfield, Missouri, cost the Union its Western Department commander, settled Missouri's fate as a contested borderland for the rest of the war, and demonstrated that the conflict would not be decided quickly.

The Situation

Missouri was the prize both sides needed. It was the largest slave state that had not seceded, with a governor, Claiborne Jackson, who was pro-Confederate and a population deeply divided between Unionist German immigrants and Southern-sympathizing rural whites. In the summer of 1861, Confederate and pro-Confederate state forces were trying to push Missouri out of the Union by force.

Brigadier General Nathaniel Lyon commanded the Union Department of the West, charged with holding Missouri. He was aggressive, politically astute — he had organized German immigrants into pro-Union militias that had saved the St. Louis arsenal in May — and dangerously overconfident. By August, his force of roughly 5,400 was outnumbered by the combined Confederate and Missouri State Guard forces under Ben McCulloch and Sterling Price: approximately 12,000 men.

The Attack

Lyon decided to attack anyway. His plan was a double envelopment — his main force striking the Confederate camp from the north while a column under Colonel Franz Sigel hit from the south. The night march went well. The dawn assault achieved surprise.

Sigel's column initially routed the Confederate forces in front of it. Then Confederate troops in gray — Sigel's men mistook them for another Union column — opened fire. Sigel's force collapsed and fled. The southern arm of the pincer was gone.

On Bloody Hill, Lyon's main force fought for three hours against Confederate counterattacks. Lyon was shot twice and killed in the fighting, becoming the first Union general officer killed in the war. His death effectively ended the Union advance.

Major Samuel Sturgis assumed command and ordered the army back to Springfield, then all the way to Rolla. The Union had 1,317 casualties; the Confederates 1,222.

The Consequence

Wilson's Creek gave the Confederacy and Missouri State Guard control of southwest Missouri for months. Price's army marched north and, in September, captured the Union garrison at Lexington, Missouri. The state was not secured for the Union until early 1862.

Lyon's aggressiveness had been both his value and his ruin: he had held Missouri in the Union when it mattered most in the summer of 1861, and then driven his outnumbered force into a fight it should not have taken. The battle that cost him his life was strategically his own creation.