The Battle of Wilson's Creek, also known as the Battle of Oak Hills, was the first major battle of the Trans-Mississippi Theater of the American Civil War. It was fought on August 10, 1861, near Springfield, Missouri.
Nathaniel Lyon was the first Union general to be killed in the American Civil War. He is noted for his actions in Missouri in 1861, at the beginning of the conflict, to forestall secret secessionist plans of the governor Claiborne Jackson.
Claiborne Fox Jackson was an American politician of the Democratic Party in Missouri. He was elected as the 15th Governor of Missouri, serving from January 3, 1861, until July 31, 1861, when he was forced out by the Unionist majority in the legislature, after planning to force secession of the state.
William Selby Harney, otherwise known among the Lakota people as "Woman Killer," "Mad Bear," and "Man-Who-Keeps-His-Word," was a Tennessee-born cavalry officer in the US Army, who became known during the Indian Wars and the Mexican–American War for his brutality and ruthlessness. One of four general officers in the US Army at the beginning of the American Civil War, he was removed from overseeing the Department of the West because of his Southern sympathies early in the war, although he kept Missouri from joining the Confederacy. Under President Andrew Johnson, he served on the Indian Peace Commission, negotiating several treaties before spending his retirement partly in St. Louis and partly trading reminiscences with Jefferson Davis and Ulysses S. Grant in Mississippi.
During the lead-up to the American Civil War, the proposed secession of Missouri from the Union was controversial because of the state's disputed status. The Missouri state convention voted in March 1861, by 98-1, against secession, and was a border state until abolishing slavery in January 1865. Missouri was claimed by both the Union and the Confederacy, had two rival state governments,, and sent representatives to both the United States Congress and the Confederate Congress.
The Battle of Carthage, also known as the Engagement near Carthage, took place at the beginning of the American Civil War on July 5, 1861, near Carthage, Missouri. The experienced Colonel Franz Sigel commanded 1,100 Federal soldiers intent on keeping Missouri within the Union. The Missouri State Guard was commanded by Governor Claiborne F. Jackson himself and numbered over 4,000 soldiers led by a hero of Mexico, Sterling Price, along with 2,000 unarmed troops who did not participate in the battle.
The Battle of Dry Wood Creek, also known as the Battle of the Mules, was fought on September 2, 1861, in Vernon County, Missouri, during the American Civil War. After his victory at the Battle of Wilson's Creek on August 10, Sterling Price and the Missouri State Guard moved further north into Missouri. A force of Union troops under James H. Lane moved from Fort Scott, Kansas to attempt an interception of Price's army, and set an ambush along Dry Wood Creek. Price's Missouri State Guard troops outnumbered Lane's Kansas troops, and after a two hour skirmish forced Lane to retreat to Fort Scott. In their retreat, Lane's troops abandoned their supplies and mules to the Missourians. Price followed up his victory by continuing his northward march, culminating in another victory at the siege of Lexington, September 13 to 20, before returning south shortly afterwards.
The First Battle of Boonville was a minor skirmish of the American Civil War, occurring on June 17, 1861, near Boonville in Cooper County, Missouri. Although casualties were extremely light, the battle's strategic impact was far greater than one might assume from its limited nature. The Union victory established what would become an unbroken Federal control of the Missouri River, and helped to thwart efforts to bring Missouri into the Confederacy.
The Price–Harney Truce was a document signed on May 21, 1861, between United States Army General William S. Harney and Missouri State Guard commander Sterling Price at the beginning of the American Civil War.
Hamilton Rowan Gamble was an American jurist and politician who served as the Chief Justice of the Missouri Supreme Court at the time of the Dred Scott case in 1852. Although his colleagues voted to overturn the 28-year precedent in Missouri of "once free always free," Gamble wrote a dissenting opinion. During the American Civil War, he was appointed as the Governor of Missouri by a Constitutional Convention after Union forces captured the state capital at Jefferson City and deposed the elected governor, Claiborne Jackson.
John Bullock Clark Sr. was a politician who served as a member of the United States Congress and Confederate Congress. Born in Kentucky, Clark moved with his family to Missouri in 1818 and began studying law. He opened a legal practice in Fayette, Missouri, in 1824. He held several positions in the local government in the 1820s and 1830s. Clark was also involved in the state militia, serving as a colonel in the Black Hawk War in 1832 and eventually rising to the militia rank of major general. In 1838, during the Missouri Mormon War, Clark was the recipient of Governor Lilburn Boggs's infamous Mormon Extermination Order, and Clark was involved in the ending stages of the conflict. In 1840, he was the Whig candidate in the 1840 Missouri gubernatorial election; accusations of Clark's involvement in an alleged plot to distribute fake ballots during the election almost resulted in a duel with Claiborne Fox Jackson.
During the American Civil War, Missouri was a hotly contested border state populated by both Union and Confederate sympathizers. It sent armies, generals, and supplies to both sides, maintained dual governments, and endured a bloody neighbor-against-neighbor intrastate war within the larger national war.
Thomas Caute Reynolds was the Confederate governor of Missouri from 1862 to 1865, succeeding upon the death of Claiborne F. Jackson after serving as lieutenant governor in exile. In 1864 he returned to the state, but was forced back into exile after the Battle of Westport.
The Missouri Constitutional Convention of 1861–1863 was a constitutional convention held in the state of Missouri during the American Civil War. The convention was elected in early 1861, and voted against secession. When open fighting broke out between Pro-Confederate governor Claiborne Fox Jackson and Union authorities, and Union forces occupied the state capital, the convention formed a provisional state government, and functioned as a quasi-legislature for several years. The convention never did produce a new constitution; that task was delegated to a new convention, elected in 1864.
William Yarnel Slack was an American lawyer, politician and military officer who fought for the Confederate States of America during the American Civil War. Born in Kentucky, Slack moved to Missouri as a child and later entered the legal profession. After serving in the Missouri General Assembly from 1842 to 1843, he served as a captain in the United States Army for fourteen months during the Mexican-American War, beginning in 1846. He saw action at the Battle of Embudo Pass and the Siege of Pueblo de Taos. Returning to a legal career, Slack became influential in his local area.
The Frémont Emancipation was part of a military proclamation issued by Major General John C. Frémont (1813–1890) on August 30, 1861, in St. Louis, Missouri during the early months of the American Civil War. The proclamation placed the state of Missouri under martial law and decreed that all property of those bearing arms in rebellion would be confiscated, including slaves, and that confiscated slaves would subsequently be declared free. It also imposed capital punishment for those in rebellion against the federal government.
The 1st Missouri Infantry Regiment evolved from one of several unofficial pro-Unionist Home Guards militia formed in St. Louis in the early months of 1861 by Congressman Francis Preston Blair, Jr. and other Unionist activists. The militia that would become the First Missouri was largely composed of ethnic Germans, although Companies K and I had significant numbers of native born American citizens and Irish-Americans. Although initially without any official standing, beginning on April 22, 1861, the four "underground" militia regiments Blair helped organize were sworn into Federal service at the St. Louis Arsenal by Captain John Schofield acting on the authority of President Lincoln.
The Provisional Government of Missouri was established on August 1, 1861 by the members of the Missouri Constitutional Convention after the evacuation of Missouri's pro-Secessionist Governor Clairborne Fox Jackson and elements of the Legislature to the southern part of the state. The Missouri State Convention, acting under authorities granted to it by the special election earlier that year, declared the office of Governor vacant, and appointed former Missouri Supreme Court Justice Hamilton Gamble Governor. Even opponents of Federal action in Missouri generally respected Gamble.
Confederate States 
