Van Dorn's bold flanking march put a Confederate army behind Union lines — but then two Confederate generals were killed in the same hour, and the attack fell apart completely.
The Battle of Pea Ridge (March 7–8, 1862) was the decisive battle for control of Missouri and northern Arkansas. Confederate General Van Dorn marched 16,500 men on a daring flanking move around the Union army, hoping to attack from the rear and destroy Curtis's 10,500-man force.
The Confederate plan required two separate wings attacking simultaneously from different directions. On March 7, both attacks developed — but on the Leetown sector, disaster struck: General McCulloch was killed by a Union sharpshooter, and his replacement James McIntosh was killed within minutes. The Confederate left wing collapsed in leadership chaos.
Native American troops under Confederate General Albert Pike fought at Leetown — the largest deployment of Native American forces in the Civil War. Several Union soldiers were scalped after the battle, causing an international incident and lasting controversy over Pike's conduct.
Price's wing at Elkhorn Tavern fought hard and actually pushed the Union forces back on the first day, but without McCulloch's wing coordinating the attack, there was no knockout blow. Van Dorn had split his forces and now could not reunite them effectively.
On March 8, Union artillery under Sigel shredded the Confederate right flank with concentrated fire. Van Dorn's army, low on ammunition after two days of fighting, had no choice but to retreat. He pulled what remained of his force south and then east, eventually crossing the Mississippi River.
The Union victory permanently ended the Confederate threat to Missouri. With Van Dorn's army transferred across the river, Arkansas was left largely undefended and gradually fell under Union control. Missouri, despite years of brutal guerrilla warfare, never formally joined the Confederacy.