Camp Jackson Affair The Camp Jackson Affair was an incident of civil unrest in the American Civil War on May 10 , 1861 , when Union military forces clashed with civilians on the streets of St . Louis , Missouri , resulting in the deaths of at least 28 people and injuries to another 100 . The highly publicized affair polarized the border state of Missouri , leading some citizens to advocate secession and others to support the Union , thus setting the stage for sustained violence between the opposing factions . Background . January through April 1861 saw furious military organization in Missouri . Pro - secessionists established Minutemen para - military groups , usually with the overt support of state authorities . In February , the St . Louis - area Minutemen were enrolled by Brigadier General Daniel Frost as companies in a new Second Regiment of the Missouri Volunteer Militia . That same month , a new law banned militia activity outside the framework of the Missouri Volunteer Militia , forcing Unionist activists to organize in secret . In March , the Missouri Constitutional Convention of 1861 voted 98 to 1 to stay in the Union but not supply weapons or men to either side if war broke out . On April 20 , eight days after the start of the war at Fort Sumter , a pro - Confederate mob at Liberty , Missouri , seized the Liberty Arsenal and made off with about 1 , 000 rifles and muskets . This sparked fears that Confederates would also seize the much larger St . Louis Arsenal , which had nearly 40 , 000 rifles and muskets — the most of any slave state . On April 23 , on orders of the War Department , Union Captain Nathaniel Lyon temporarily replaced Brigadier General William S . Harney as ( acting ) Commander of the U . S . Army ' s Western Department . Lyon began enlisting and arming St . Louis Unionist volunteers , an action previously ordered by the Secretary of War , but not acted on by General Harney . Most of Lyon ' s early recruits were German immigrants and members of the Wide Awakes political organization . According to one estimate , 80 % of the volunteers in the first Missouri Volunteer regiments were Germans . The Germans in particular were unpopular with many native - born Missourians with Southern backgrounds , who deeply resented their anti - slavery views . On the orders of the War Department , in the early morning hours of April 26 , U . S . Regulars , Illinois state troops , and Missouri volunteers loaded 21 , 000 of the Arsenal ' s 39 , 000 weapons on the steamer " City of Alton " , which carried them across the river to Illinois . In mid - April , Missouri Governor Claiborne Fox Jackson , who had been elected on the ticket of the ( Unionist ) Douglas faction of the Democratic party , but privately supported secession , had sent two pro - secessionist militia officers ( Colton Green and Basil Wilson Duke ) to Confederate President Jefferson Davis , with a letter asking for heavy artillery with which to attack the St . Louis Arsenal . Around May 1 , Jackson called out the Missouri Volunteer Militia for " maneuvers " . These took place about 4 . 5 miles northwest of the arsenal at an encampment christened " Camp Jackson " by the militiamen and located at Lindell ' s Grove ( then outside the city of St . Louis , and today the site of the campus of St . Louis University on Lindell Boulevard ) . On May 9 , the steamer ' J . C . Swon ' delivered the Confederate aid : two 12 - pound howitzers , two 32 - pound siege guns , 500 muskets , and ammunition in crates marked as Tamoroa marble . The munitions had been captured by the Confederates when they seized the Federal arsenal at Baton Rouge . MVM officers met the shipment at the St . Louis riverfront , and transported it to Camp Jackson , six miles inland . Conflict . Based on the presence of the " stolen " U . S . artillery , and strong evidence of state militia conspiracy against the U . S . government , on May 10 , Lyon marched on Camp Jackson with about 6 , 000 Federally enrolled Missouri Volunteers and U . S . Regulars , who forced the surrender of 669 members of the Missouri Volunteer Militia under General Daniel M . Frost . The militiamen refused to take the oath of allegiance to the Federal government , so Lyon placed them under arrest and marched the militia to the arsenal through downtown St . Louis . There , he provided them with a parole and ordered them to disperse . But the lengthy march was widely viewed as a public humiliation for the state forces , and angered citizens who had gathered to watch the commotion . Tensions quickly mounted on the streets as civilians hurled rocks , paving stones , and insults at Lyon ' s troops . The heavily German Missouri Volunteer units were particularly targeted by the mob and shouts of " Damn the Dutch " were hurled at them from the crowd . Exactly what provoked the shooting remains unclear , but the most common explanation is that a drunkard stumbled into the path of the marching soldiers , and fired a pistol into their ranks , fatally wounding Captain Constantin Blandowski of the Third Missouri Volunteers . The volunteers , in reaction , fired over the heads of . . . and then into . . . the crowd , killing some 28 people , some of whom were women and children , and wounding as many as 50 more . The incident sparked several days of rioting and anti - German animosity in St . Louis . On May 11 , German Volunteers were fired upon from windows at 5th and Walnut streets ; they returned fire into the mob . Col . Henry Boernstein , publisher of the " Anzeiger des Westens " a prominent German Language newspaper in St . Louis and commander of the 2nd Regiment of Missouri Volunteers , remarked in his memoirs that he gave several of his men leave to visit their families on the morning of May 11 and that , “ Most of them did not return … until it grew dark , with clothing torn , faces beaten bloody , and all the signs of having suffered mistreatment … Two of them never returned and they were never heard of again . ” Rumors spread throughout the city that the Germans were planning to murder the American population of the city ; many wealthy St . Louisians fled to Illinois or the Missouri interior . Martial law was imposed , and with the arrival of Federal Regulars to relieve the German volunteers , the violence came to an end . Aftermath . Nativism , mistrust of the Federal government , slavery , and states rights issues all played roles in provoking the incident . The Affair polarized the state between Union and Confederate supporters . Previously most Missourians had advocated neutrality . However the Camp Jackson Affair forced most Missourians to take a side . Some former " Conditional Unionists " , including former Governor Sterling Price , now advocated secession . But ultimately the actions of Lyon and the St . Louis German community did much to ensure Missouri ' s continued loyalty to the Union . And in the years following the war , the Germans would gain a reputation as " saviors of Missouri . " Governor Jackson exploited the Affair to resubmit the stalled " Military Bill " which would put the state on a war footing , create a new state military force , and granted the Governor wide executive powers . On May 11 , the Missouri General Assembly approved the measure , which created the Missouri State Guard to resist the Union invasion with Sterling Price as its Major General . Unionists described the bill as a " secession act in all but name " . Critics also observed that since it stated that all adult men were to be considered to be reserves of the State Guard , and granted the Governor wide powers as commander of the Guard , it had the effect of making Governor Jackson dictator of the state . The following day , Major General Price and Brigadier General William S . Harney ( Commander of the Western District , which included Missouri ) signed the Price - Harney Truce leaving the Federal military in charge of St . Louis , and allowing state forces to maintain order in the rest of the state . Many Missouri unionists considered the agreement to be a capitulation to Jackson and the secessionist faction . Unionists outside of St . Louis reported harassment by secessionists , many fleeing to St . Louis for refuge . On May 30 , Harney was relieved of command by Congressman / Colonel Francis P . Blair , Jr who had previously been granted the right to do so at his discretion by President Lincoln . Lyon was promoted to Brigadier General of Volunteers and assigned command of all the Union forces in Missouri . On June 11 , in a face - to - face meeting at St . Louis ' Planter ' s House hotel Brigadier General Nathaniel Lyon and Governor Jackson failed to reach a new agreement . After over four hours of argument ( much of it over the powers claimed by Jackson in the Military Bill ) Lyon abruptly ending the meeting declaring " This means war . In an hour one of my officers will call on you and conduct you out of my lines . Jackson retreated to the state capitol at Jefferson City , and then evacuated the city on June 12 , joining newly assembled State Guard troops near Boonville . Lyon occupied the capitol without resistance , and pursued Jackson with approximately 1 , 400 volunteers and U . S . Army regulars . Against the advice of his senior officers , Governor Jackson exercised his authority as Commander - in - Chief and ordered the State Guard to make a stand at Boonville . In the resulting battle on June 17 Lyon ' s troops routed the State Guard . Jackson , the State Guard , and pro - secessionist members of the General Assembly retreated to southwest Missouri , near the Arkansas border , leaving most of the state under Federal control . The Missouri Constitutional Convention , elected in February 1861 to amend the state constitution and decide the issue of secession , convened on July 22 and declared the office of Governor vacant due to Jackson ' s withdrawal from the state capitol ( among other issues ) . The Convention then voted to appoint former Chief Justice of the Missouri Supreme Court and conservative Unionist Hamilton Rowan Gamble as Governor of the Provisional Government of Missouri . Gamble ' s government was recognized by the Lincoln administration , and controlled its own military force , the ( new ) Missouri State Militia in battles against guerrillas and the State Guard . Brigadier General Lyon , commanding an army of about 6 , 000 men ( U . S . Regulars and volunteer troops from Missouri , Kansas , and Iowa ) pursued Jackson and the State Guard as far as Springfield on August 1 . By that time the Missouri State Guard had linked up with Arkansas State Troops and a Confederate army under General Ben McCulloch , creating a combined force of over 12 , 000 men . Lyon decided to retreat to his rail head at Rolla , but attempted to deliver a preemptive attack to damage the secessionist force and allow his troops to withdraw safely . The resulting August 10 Battle of Wilson ' s Creek , fought ten miles south of Springfield , was a bloody affair , lasting over five hours . The battle ground down to a stalemate , with the outnumbered Federals holding off three charges on their position on Bloody Hill . The battle finally ended when Lyon was killed leading a charge , and his successor in command , Major Samuel Sturgis , concerned about his ammunition supplies ordered a withdrawal . The exhausted Confederates did not immediately pursue . As a result of the battle , Price and Jackson were left in control of parts of south and southwestern Missouri until the Battle of Pea Ridge on March 6 – 8 , 1862 . In addition , the withdrawal of Federal troops allowed Jackson to establish a " government in exile " in the southwest Missouri town of Neosho . On October 28 , 1861 pro - secession elements of the General Assembly met in the town ' s Masonic Hall and ( reportedly ) passed an Ordinance of Secession , making Missouri a short lived independent republic . On November 28 , 1861 the Confederate Congress accepted the Jackson government ' s petition and admitted Missouri as the " twelfth Confederate state " . The legality of the Neosho secession ( even under Confederate law ) has been questioned by many historians who : question whether a proper quorum of the General Assembly was present ; note that the General Assembly had previously granted the power over secession action to the Constitutional Convention ; and note that under Missouri state law an Ordinance of Secession required confirmation by a plebiscite of the state ' s voters ( which never occurred ) .