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.
In August, Confederates under Brigadier General Benjamin McCulloch and Missouri State Guard troops under Maj. Gen. Sterling Price approached Brig. Gen. Nathaniel Lyon's Army of the West, camped at Springfield. On August 10, Lyon, in two columns commanded by himself and Col. Franz Sigel, attacked the Confederates on Wilson Creek about 10 miles (16 km) southwest of Springfield. Confederate cavalry received the first blow and retreated from the high ground. Confederate infantry attacked the Union forces three times during the day, but failed to break through. Eventually, Sigel's column was driven back to Springfield, allowing the Confederates to consolidate their forces against Lyon's main column. When Lyon was killed, Major Samuel D. Sturgis assumed command of the Union forces. When Sturgis realized that his men were exhausted and lacking ammunition, he ordered a retreat to Springfield. The battle was reckoned as a Confederate victory, but the Confederates were too disorganized and ill-equipped to pursue the retreating Union forces.
Although the state remained in the Union for the remainder of the war, the battle effectively gave the Confederates control of southwestern Missouri. The victory at Wilson's Creek also allowed Price to lead the Missouri State Guard north in a campaign culminating at the siege of Lexington, Missouri.
Background
Military and political situation
At the beginning of the American Civil War in 1861, the state of Missouri was a politically divided border state. Permitting slavery, the state had long-standing cultural and economic ties to the Southern United States, although these had declined in the years leading up to the outbreak of war. While the state's newly-elected Governor Claiborne Fox Jackson did not openly support seceding from the United States and joining the Confederate States of America, he harbored pro-Confederate sympathies. The outgoing governor had appealed to the state to maintain "armed neutrality" during the conflict. On April 20, a secessionist mob seized the arsenal in Liberty, Missouri, increasing Union concerns in the state. Unionist activities in the state increased as well.
Under an 1858 state law governing the militia, Jackson called out the Missouri Volunteer Militia (MVM) for mustering and training. Those companies from the St. Louis area encamped at Lindell's Grove, creating a camp they named Camp Jackson. These militia numbered close to 900 men under the command of Brigadier General Daniel M. Frost and were mostly pro-secession and pro-Confederate. Jackson had secretly obtained two cannons from the Confederate government, and Jackson and Frost intended to use the militia to capture the St. Louis Arsenal. Captain Nathaniel Lyon of the United States Army was aware of these developments and was concerned the militia would move on the arsenal. In late April, Lyon had mustered five regiments of Home Guard into Union service; four of the five regiments were predominantly German. He received further authorization April 30 to raise another five regiments as a reserve under the command of Thomas W. Sweeny. These troops were given arms by the federal government but were not formally mustered into the United States Army; this was considered an extraordinary measure. Lyon kept aware of the activities of the militia camp; he is alleged to have scouted in the camp in a carriage while disguised as an old blind woman. On the morning of May 10, Lyon led his troops in converging columns against Camp Jackson. With Lyon's armed men around the camp, Frost surrendered the militia encampment to Lyon under protest. Lyon paraded his prisoners through the St. Louis streets. Crowds expressed anti-German and pro-Confederate sentiments. A drunk fired a shot at the soldiers after an altercation, and further firing followed. Some of the German troops opened fire on the crowd. Three prisoners, two soldiers, and twenty-eight civilians were killed, with roughly seventy-five more civilians wounded. This became known as the Camp Jackson affair.
News of the events at Camp Jackson led the previously pro-Union state legislature to pass legislation that veered towards secession. On May 14, what was known as the "military bill" was officially passed. This created the Missouri State Guard (MSG), a new militia organization. The MSG was organized into nine divisions. Sterling Price, a former moderate who had objected to the events at Camp Jackson, was placed in command with the rank of major general. One division was never effectively formed due to Union control of the St. Louis area, and the others varied in size from roughly 400 men to over 2,000. The divisions were based on geography, and were not organized in the traditional military sense. Seeing Missouri's tilt to the South, William S. Harney, the Federal commander of the U.S. Army's Department of the West (which included Missouri) negotiated the Price-Harney Truce on May 21, which nominally created cooperation between the U.S. Army and the MSG to maintain order in Missouri. Under the agreement, the Missouri government would keep peace in the state; so long as the situation remained peaceful, Harney would not intervene with the military. If intervention was necessary, Harney agreed to cooperate with the state forces in peace-keeping. Effectively, this required the federal government to be neutral in the conflict.
Initial military actions
After complaints by Missouri Unionists, Harney was relieved and Lyon promoted to Brigadier General, actions that undermined the fragile truce with Price. However, instead of Lyon replacing Harney as departmental commander, Missouri was transferred from the Department of the West to the Department of the Ohio. On June 11, Lyon and Francis Preston Blair Jr. met with Jackson and Price at the St. Louis Planter's House Hotel in a last attempt to avoid a resumption of fighting. Jackson offered to disband the state militia under the condition that Federal forces be restricted to the St. Louis metropolitan area, but Lyon rejected it. The historians William Garrett Piston and Richard Hatcher believe that Jackson and Price, with their forces unready for battle, were trying to buy time. In a book published in 1886, Colonel Thomas Snead, by then the only surviving witness to that meeting, stated that the meeting ended with Lyon saying:
...rather than concede to the State of Missouri for one single instant the right to dictate to my government in any matter however unimportant, I would see you, and you, and you, and you, and every man, woman, and child in the State, dead and buried. This means war.
Lyon sent a force under Sweeny to Springfield, although Sweeny remained in St. Louis for a time with the troops commanded by Franz Sigel in his absence. Another prong of the advance was commanded by Lyon personally and moved from St. Louis towards the state capital of Jefferson City, which was captured on June 15. Further troops were intended to move from Fort Leavenworth in Kansas and join Lyon in western Missouri. On June 17, Lyon routed a portion of the Missouri State Guard in the Battle of Boonville. Price, Jackson, and the Missouri State Guard withdrew south. Sigel moved to attack Jackson's militia forces in southwestern Missouri but was defeated in the Battle of Carthage on July 5. In light of the crisis, the delegates of the Missouri Constitutional Convention that had previously rejected secession in February reconvened in late July. The convention declared the offices of governor, lieutenant governor, and secretary of state vacant and selected Hamilton Rowan Gamble to be the new provisional governor.
After the defeat at Carthage, Sigel withdrew to Springfield. On July 7, Lyon and the forces with him were joined at Clinton, Missouri, by a force that had arrived from Kansas commanded by Major Samuel D. Sturgis. These troops with Lyon reached the Springfield area on July 13, although Lyon did not immediately allow his troops to enter Springfield until they had been resupplied, as a precaution against looting. Price and Jackson counted on support from Confederate Brigadier General Benjamin McCulloch. McCulloch and Arkansas militia general N. Bart Pearce entered Missouri on July 4, but withdrew back to Arkansas two days later. Price gathered his troops at Cassville on July 28, where they were joined by McCulloch's troops again on July 29, with Pearce's men following two days later. Price and McCulloch developed plans to attack Springfield and put their troops in motion. Having heard rumors that Missouri State Guard troops were moving to occupy a town northwest of Springfield, aware that he was unlikely to get reinforcements from his commanding officer John C. Frémont, and aware of the concentration at Cassville, Lyon marched his troops out of Springfield on August 1 to confront Price and McCulloch's forces. Lyon's vanguard routed James S. Rains' Missouri state guard forces on August 2 in the Battle of Dug Springs. Short on supplies, Lyon withdrew to Springfield on August 4 after a council of war. On August 3 and 4, Price urged McCulloch to attack, but McCulloch was hesitant due to doubts about the quality of the Missouri State Guard which had grown stronger after the fight at Dug Springs. After receiving communications regarding Confederate operations in southeastern Missouri, McCulloch decided to order an advance. On August 6, his force was encamped at Wilson Creek, 10 miles (16 km) southwest of the city. Price was informed by civilians on August 8 that Lyon was considering a withdrawal from Springfield, leading Price to advocate for an assault. McCulloch was initially unwilling to attack, but after a council of war the next day in which Price threatened to attack without McCulloch, agreed to an attack on the morning of April 10. This attack was called off due to a rainstorm late on April 9, which would have dampened the soldiers' gunpowder, preventing them from firing.
Outnumbered, with many of his men's enlistments expiring or about to expire, and aware that he would not be receiving assistance from St. Louis, Lyon's only logical option was to withdraw to Rolla, Missouri. However, the naturally aggressive Lyon did not want to withdraw without a fight; it was hoped that such a fight would delay or discourage pursuit. The decision to attack was made on August 8, with the offensive movement to begin late the next day. At a council of war on the afternoon of August 9, Sigel proposed striking McCulloch in a pincer movement, which would split the already outnumbered Union force; he planned to lead 1,200 men in a flanking maneuver while the main body under Lyon struck from the north. Lyon had previously rejected an earlier plan from Sigel involving an attack by divided forces. While other officers opposed the decision, Lyon concurred with Sigel's plan, which was adopted. The Union army marched out to battle late on August 9; it was rainy for part of the march. Part of Lyon's command was left in Springfield,
tasked with guarding the city and preparing for an evacuation in case of defeat.
Opposing forces
Union
Lyon's army was known as the Army of the West. This army was formed from three bodies of troops: one that had accompanied Lyon south from Boonville; troops that had moved from Fort Leavenworth, Kansas, under the command of Sturgis; and a force that had moved down from St. Louis commanded by Sweeny. Sweeny's troops had left St. Louis before he did, and these soldiers were commanded by Sigel earlier in the campaign. In late July, Lyon organized his command into four brigades, commanded by Sturgis, Sigel, George L. Andrews, and George W. Dietzler. Many of Lyon's soldiers earlier in the campaign had enlistment terms of only ninety days, and in July roughly 2,000 soldiers left Lyon's army to be discharged in St. Louis. At the battle, Lyon's force numbered 5,431 men. Further troops remained behind in Springfield, including a 1,200-man Home Guard unit.
Confederate
McCulloch's army lacked a formal name, although he referred to it as the Western Army. Pearce referred to it as the Army of Arkansas or the Consolidated Army. Price did not consider the Missouri State Guard to be party of the Confederacy, and in June Jackson had delivered a speech arguing that the Missourians were bound to the United States Constitution, but that loyalty to Missouri bore precedence and that the United States government itself was behaving in an unconstitutional manner. While Pearce's troops were clearly subordinate to McCulloch, the same could not be said about Price's MSG. Price eventually offered overall command to McCulloch, who accepted the responsibility. Many of the soldiers were armed only with civilian weapons, and roughly 2,000 unarmed MSG soldiers accompanied the march. The presence of both these unarmed men and a number of Missouri camp followers breached an earlier agreement reached between Price and McCulloch. Including the unarmed Missouri militia, the Western Army numbered an estimated 12,125 men at Wilson's Creek. McCulloch viewed the MSG as undisciplined and unreliable.