Terry Beckenbaugh of the Command and General Staff College at Fort Leavenworth discusses the first Civil War battle fought west of the Mississippi River, which took place in southwestern Missouri. On August 10, 1861, Union General Nathaniel Lyon — who was encamped at Springfield with nearly 6,000 men — led a surprise attack on 12,000 secessionist troops camped at Wilson’s Creek. While the Confederates won the battle, they were left in no condition to pursue the retreating Federal forces, and Missouri remained under Union control.