Union Captain Nathaniel Lyon leads 6,000 federal Missouri Volunteers and U.S. Regulars against the secessionist "Camp Jackson" arsenal. He then marches 669 of the captured militiamen through the streets of St. Louis, prompting a riot. In the chaos, Lyon's unseasoned volunteers fire into the crowd, killing some 28 onlookers and wounding nearly 100 more. The incident becomes known as the "Camp Jackson Affair," but Lyon later receives a promotion to brigadier general on July 2, 1861.