Months of tension reached a climax in Missouri on Monday, June 17, 1861, near the little town of Boonville.
A meeting had been set up days earlier in St. Louis to try to bring some peace to the divided state, but it had ended with Union General Nathaniel Lyon declaring war on the pro-Southern leaders, Governor Claiborne Jackson and General Sterling Price.
After the meeting, Jackson and Price fled to the state capital of Jefferson City. They quickly decided that the capital could not be held and retreated with the State Guard northwest to Boonville. They needed time to consolidate the militia forces at Boonville and Lexington, and to train and arm them. But time was the one thing Lyon did not intend to give them.
Price had planned to retreat from Boonville if Lyon's army showed up, but he became ill with dysentary and traveled on to Lexington where more militia forces were gathering, leaving the governor in charge. Jackson, fearing the political price of another retreat, decided to have the showdown at Boonville.
Lyon's army of 1700, two volunteer brigades, a company of regulars and an artillery battery, advanced down the Rocheport Road toward Boonville. They ran into Colonel John Marmaduke's regiment of militia, some 500 men, positioned around a house, its outbuildings and a wheat field. Union artillery fire drove the militiamen back, but they quickly regrouped on a nearby ridge. More artillery fire drove the militiamen back through their camp to the fairgrounds east of town. Supported by fire from an eight-inch howitzer aboard the
Augustus McDowell on the nearby Missouri River, the Union forces flanked the line of militia and the retreat quickly turned into a rout. The militia disintegrated; the men scattering in all directions.
The bulk of the fighting lasted less than thirty minutes and casualties were light on both sides, but the consequences were huge. The Union army now had control of the Missouri River and much of the state, including the state capital. Although the fighting in Missouri would continue throughout much of the war, Governor Claiborne Jackson's dream of putting the state in the Confederacy were over. Much of the militia would retreat with Jackson to the extreme southwestern corner of the state and attempt to regroup.
Also on this date, in Greenville, Tennessee, delegates met in a convention to discuss ways to keep east Tennessee in the Union.
The pro-Unionists of East Tennessee followed a script that was very similar to the one the pro-Unionists of western Virginia followed. The main difference was that the Tennesseans did not have a Union army nearby to help them out.
The east Tennesseans met in Knoxville on May 30-31 to protest Governor Isham Harris's efforts to align the state with the Confederacy. One of their biggest grievances was that Harris had called for a statewide referendum on June 8 to approve an "Ordinance of Secession," skipping a convention to debate the issue. After many speeches condemning the governor and the state legislature for their disregard of the U.S. Constitution, the delegates agreed to meet again if Tennessee voters approved secession.
The Greeneville convention got underway on June 17. The first two days were spent mainly on organizing the convention, debating voting rules, and speechmaking. On the third day, the delegates heard two similar sets of resolutions. The first called for the formation of military companies, and pledged retaliation if any convention members were harmed or if the region were occupied by Confederate forces. The second set of resolutions was less violent in nature, mainly resolving to send a memorial to the state legislature seeking its consent for the region to form a separate state.
The second set of resolutions was adopted after much debate. The memorial was sent to the legislature, which rejected the convention's bid for statehood. The legislature promised not to pass any conscription laws, but the governor sent Confederate troops into the region to protect secessionists there. Many delegates fled to the north or went into hiding.
In other news, in Washington, Thaddeus S. C. Lowe ascended in a tethered balloon some 500 feet above the White House to demonstrate the effectiveness of aerial reconnaissance. Using a telegraph set he communicated with Lincoln, "I have the pleasure of sending you this first dispatch ever telegraphed from an aerial station..." In July 1861, Lowe would be named Chief Aeronaut of the Union Army Balloon Corps. He made several successful observations, but disputes over his operations and his pay forced his resignation in 1863.