Four battles were fought at Boonville during the Civil War: the first battle forms the main subject of this article. The battle itself was actually little more than a skirmish, but it was one of the first significant land actions of the war, and had grave consequences for Confederate hopes in Missouri.
At the onset of the Civil War, Missouri, like many border states in the Union, was deeply divided over whether to support the United States under Abraham Lincoln, or join the Confederacy under Jefferson Davis. Claiborne F. Jackson, the pro-Southern governor, wanted his state to secede, but Missouri's overall sentiment was initially neutral. An elected State convention did not pass a secession ordinance, as Jackson had hoped it might.
However, pro-secession elements did not let this setback dissuade them. They seized the small Federal armory in Liberty, Missouri, planning to subsequently confiscate a much more sizable stock of weapons located at the St. Louis Arsenal. This plot was thwarted by an energetic young officer, Captain Nathaniel Lyon. Lyon allied himself with local politician Frank Blair and anti-slavery German immigrants in St. Louis to secure the arsenal for the Union; in the process, he used mostly German Union militia units to capture the Missouri State Guard as they drilled at nearby Camp Jackson on May 10, 1861. When Lyon unwisely attempted to march his prisoners through the streets of St. Louis, a deadly riot erupted. With the latent pro-Southern sentiments of the state inflamed, the Missouri legislature promptly passed a bill creating the Missouri State Guard, which commenced forming from the old militia core.
Attempts were made to reconcile the two sides. The initial call-up of the Missouri State Guard was halted by the legislature, and an informal truce was negotiated between General William S. Harney of the U.S. Army and Sterling Price, commander of the Missouri State Guard. However, the appointment of Nathaniel Lyon as a brigadier general and his placement over all Federal forces in Missouri in Harney's place led to a collapse of negotiations on June 11, 1861, with Lyon angrily insisting he would kill every man, woman and child in the state before compromising his right to operate against Missouri Rebels as he saw fit.
Governor Jackson and General Price fled toward the capital at Jefferson City, arriving there on June 12. After quickly concluding that the city could not be held, they departed for Boonville the next day. General Lyon promptly set out after them by steamboat, with two Federal volunteer regiments, a company of U.S. regulars and a battery of artillery—about 1,700 men in all. His goal was to seize the capital and disperse the State Guard.
Price hoped to buy enough time to consolidate State Guard units from Lexington and Boonville, though he planned to withdraw from Boonville if Lyon approached. State Guard Colonel John S. Marmaduke's unit began organizing at Boonville, while Brig. Gen. Mosby M. Parsons was instructed to take up a position twenty miles to the south in Tipton. At this juncture, Price left Boonville due to illness and joined the forces assembling at Lexington. This was unfortunate, as it left the governor—a politician—in charge. Instead of retreating, Jackson decided to make a stand, because he feared political fallout if he made another withdrawal. Many of his men were eager to face the enemy, but they were armed only with shotguns and hunting rifles, and lacked sufficient training to fight effectively at the time. Marmaduke was opposed to giving battle, but he reluctantly assumed command of the waiting state forces.
Lyon, meanwhile, had reached Jefferson City on June 15, learning that Jackson and Price had retreated towards Boonville. Leaving behind 300 Federals to secure the capital, Lyon resumed his pursuit of Price on June 16, landing about eight miles below Boonville on June 17. Informed of Lyon's approach, Jackson attempted to call up Parsons' command at Tipton, but it was unable to arrive in time.
After disembarking, Lyon's troops marched along the Rocheport Road toward Boonville at around 7 AM. Marmaduke's ill-equipped State Guard companies waited on a ridge behind the bluff, totalling about 500 men. They had no artillery support, since it was all with Parsons at Tipton. Inexplicably, Governor Jackson, observing from a mile or so away, held his only reasonably-disciplined and organized command (Captain Kelly's company) in reserve; it would take no part in the battle.
Lyon's command encountered State Guard pickets as they approached the bluffs, but Lyon deployed skirmishers and continued to push his men forward rapidly. The Union artillery quickly displaced sharpshooters stationed in the William Adams house, while Union infantry closed with the line of guardsmen and fired several volleys into them, causing them to retreat. This portion of the fighting lasted barely 20 minutes. Some attempts were made to rally and resist the Federal advance, but these collapsed when a Union company flanked the Guard's line, supported by a siege howitzer on one of Lyon's riverboats. As Marmaduke feared, the Guard's retreat rapidly turned into a rout. The guardsmen fled back through Camp Bacon and the town of Boonville; some continued on to their homes, while the rest retreated with the Governor to the southwest corner of Missouri. Lyon took possession of Boonville at 11 AM.
The short fight at Boonville and the State Guard's precipitate retreat earned the battle the nickname of "The Boonville Races."
Federal casualties were light, with five men killed or mortally wounded and about seven less seriously injured. There are no reliable figures of casualties for the Missouri State Guard: only a few are known to have been killed, and probably a dozen or so were wounded, while about 80 were captured. Lyon seized the State Guard's supplies and equipment, which included two iron 6-pounder cannon without ammunition, 500 obsolete flintlock muskets, 1200 pair of shoes, a few tents, and food.
The real impact of the Battle of Boonville was strategic, far out of proportion to the minimal loss of life. The Battle of Boonville effectively ejected the secessionist forces from the center of Missouri, and secured the state for the Union. Price realized he could not hold Lexington and retreated, though he would return three months later to re-take the city. Secessionist communications to the strongly pro-Confederate Missouri River valley were effectively cut, and would-be recruits from slave-owning regions north of the Missouri River found it difficult to join the Southern army. Provisions and supplies also could no longer be obtained from this section of the state.
A second result of the battle was demoralization. While the Missouri State Guard would fight and win on other days (most notably at Wilson's Creek and Lexington just two and three months later, respectively), it was badly dispirited by this early defeat. Lyon's victory gave the Union forces time to consolidate their hold on the state, while Marmaduke's disappointment led him to resign from the Missouri State Guard and seek a direct Confederate commission. Marmaduke and Price would team up again during Price's great Missouri Raid of 1864, culminating in their defeat at the Battle of Westport on October 23 of that year, which in turn put an end to significant Confederate operations in the state.
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