June 17, 1861
“This means war!” hot-headed Union Gen. Nathaniel Lyon told Missouri’s secessionist Gov. Claiborne F. Jackson at their June 11, 1861, conference in St. Louis. Rejecting Jackson’s proposal for Missouri’s neutrality and the demand that U.S. troops abandon the state, Lyon stormed out of the meeting and immediately issued orders for his soldiers to advance on Jefferson City — the state capital. The next day Jackson called for 50,000 state militiamen to prevent what he called the overthrow of the state government by federal forces.
Upon arriving in Jefferson City on the 14th, Lyon and his 2,000 troops found that Jackson and the secessionist state government had fled up the Mssouri River toward Boonville, 50 miles away. Lyon quickly formed a provisional Unionist state government and left a garrison at Jefferson City to preserve order. He then loaded the rest of his force into three steamers and proceeded up the river in pursuit. Lyon disembarked his men several miles below Boonville and, marching along the river road, came upon a small blocking force of secessionists under the command of Col. John S. Marmaduke.
After a brief cannonade Lyon ordered an attack, and the ill-armed and outnumbered Rebel force turned and fled in confusion. Watching from a distant hill, Jackson saw the disastrous result of the engagement and joined his troops in their southward flight.
In military terms the fight at Boonville was rather insignificant and casualties on both sides were very light. But the encounter was a serious blow to Missouri’s secessionists. The Union had firm control of the Missouri River, leaving the pro-Southern sections of Missouri north of the river cut off and unable to aid or receive aid from their comrades to the south. The duly elected secessionist governor and his followers were forced to flee, retreating into southwest Missouri. There every effort was made to concentrate men and arms to contest Lyon’s conquest of Missouri.
Fascinating Fact: One of Lyon’s men wrote: “We were both missionaries and musketeers. When we captured a man we talked him nearly to death. In other respects we treated him humanely. the Civil War was a battle of ideas interrupted by artillery.”