Nathaniel Lyon Nathaniel Lyon ( July 14 , 1818 – August 10 , 1861 ) was the first Union general to be killed in the American Civil War and is noted for his actions in the state of Missouri at the beginning of the conflict . Some credit his quick action and hard line Unionism for stopping the Missouri secession movement . Others question his influence peddling and his role in events such as the Camp Jackson Affair , which inflamed many Missourians on the secession issue ( See Missouri secession . ) There is no question that he was the first Union General to take the offensive . He graduated out of the Military Academy 11th of a class of 52 in 1841 , he fought the Seminole Indians in Florida , as well as in the Mexican American War . During the war he received several brevet promotions for gallantry under fire at the battles of Mexico City , Contreras , and Churubusco . He was then sent to posts in California where he participated in several Native American massacres . He was then reassigned to Fort Riley in Kansas , where he began to develop strong support for the Union as a result of the political climate developing in the state , known as “ Bleeding Kansas . ” In February 1861 , Lyon was made commander of the Union arsenal in St . Louis , Missouri , where tensions grew between the Union soldiers stationed there and the secessionist governor of the state , Claiborne Jackson . When the Civil War broke out , Jackson refused to send volunteers from the state to fight for Abraham Lincoln . Instead , Jackson had the militia muster outside the city to begin training in preparation to join Confederate forces . On May 10 , 1861 , Lyon and his troops surrounded the pro - Confederate Missouri militia under General D . M . Frost , and forced their surrender . While marching his captured prisoners through St . Louis , many citizens began to riot , and provoked the Camp Jackson Affair , during which Lyon ordered his troops to fire into the rioters . On May 17 , 1861 , Lyon was promoted to brigadier general and was given command of Union troops in Missouri . On August 10 , 1861 the Union forces met a combined force of the Missouri Militia and Confederate troops under the command of Ben McCulloch near Springfield , Missouri , during the battle of Wilson ’ s Creek . Nathaniel Lyon was killed during the battle while trying to rally his outnumbered soldiers . Although the Confederate forces would win the Battle of Wilson ’ s Creek , Lyon ’ s efforts prevented the State of Missouri from joining the Confederacy . Early life and career . Lyon was born on a farm in Ashford , Connecticut , son of Amasa and Kezia Knowlton Lyon . As a boy he hated farming . His relatives had fought in the American Revolutionary War and he was determined to follow in their footsteps . In 1837 he applied to the United States Military Academy and graduated eleventh in his class of 52 cadets in 1841 . He was assigned to the 2nd U . S . Infantry regiment after graduation and served with them in the Seminole Wars and the Mexican - American War . Despite denouncing American involvement in the Mexican War , he was promoted to first lieutenant for " conspicuous bravery in capturing enemy artillery " at the Battle for Mexico City and received a brevet promotion to captain for Contreras and Churubusco . He was then posted to the frontier , where he participated in the massacre of Pomo Native Americans at Clear Lake , California , the 1850 " Bloody Island Massacre . After being reassigned to Fort Riley , Kansas , Lyon became staunchly antislavery . He did not support the radicalism of the abolitionists , and came to support the Republican Party while serving in the border wars known as " Bleeding Kansas . " In January 1861 , he wrote about the secession crisis , " It is no longer useful to appeal to reason , but to the sword . " St . Louis Arsenal . In March 1861 , Lyon arrived in St . Louis in command of Company B of the 2nd U . S . Infantry . At the time the population and state of Missouri were relatively neutral in the dispute between North and South , but Governor Claiborne F . Jackson was a strong Southern sympathizer , as were many of the state legislators . Lyon was accurately concerned that Jackson meant to seize the federal arsenal in St . Louis if the state seceded and that the Union had insufficient defensive forces to prevent the seizure . He attempted to strengthen the defenses , but came into opposition from his superiors , including Brig . Gen . William S . Harney of the Department of the West . Lyon employed his friendship with Francis P . Blair , Jr . , to have himself named commander of the arsenal . When the Civil War broke out and President Abraham Lincoln called for troops to put down the Confederacy , Missouri was asked to supply four regiments . Governor Jackson refused the request and ordered the Missouri State Guard to muster outside St . Louis under the stated purpose of training for home defense . Lyon himself had been extensively involved in the St . Louis Wide Awakes , a pro - union paramilitary organization that he intended to arm from the arsenal and muster into the ranks of the federal army . Upon obtaining command of the arsenal , Lyon armed the Wide Awake units under guise of night . Lyon had most of the excess weapons in the arsenal secretly moved to Illinois . Lyon was aware of a clandestine operation whereby the Confederacy had shipped captured artillery from the U . S . arsenal in Baton Rouge to the Missouri State Militia camp in St . Louis . Lyon allegedly disguised himself as a farm woman to spy on the State Guard ' s camp and then claimed that he had uncovered a plan by Jackson to seize the arsenal for Missouri troops . On May 10 he directed the Missouri volunteer regiments and the 2nd U . S . Infantry to the camp , forcing its surrender . Riots broke out in St . Louis as Lyon marched his prisoners through the city to the St . Louis Arsenal . The event provoked the Camp Jackson Affair of May 10 , 1861 , in which Lyons ' troops opened fire on a crowd of civilians injuring at least 75 and killing 28 . Two federals and three militia were also killed and others were wounded . The source of the first shot is disputed , some witnesses claiming it was a drunken rioter , others claiming it was unprovoked . Lyon was nonetheless promoted to brigadier general May 17 . and given command over the Union troops in Missouri May 31 , 1861 as commander of the Department of the West . Pursuit of Jackson . In June , after meeting personally with Jackson in St . Louis in a futile attempt to renew the Harney agreement , Lyon declared war against Jackson and the Missouri State Guard . The governor fled first to the capitol at Jefferson City , and then retreated with the state government to Boonville . Lyon moved up the Missouri River and captured Jefferson City on June 13 . He continued the pursuit and on June 17 he defeated a portion of the Missouri State Guard at the Battle of Boonville . The governor , Missouri State Government , and the Missouri State Guard retreated to the southwest . Lyon installed a pro - Union state government in its place and removed the state ' s attorney general , J . Proctor Knott , a Unionist who had stayed behind . Lyon assumed command of the Army of the West on July 2 . Lyon reinforced his army before moving southwest as well . Battle of Wilson ' s Creek . By July 13 , Lyon was encamped at Springfield , Missouri , with about 6 , 000 Union soldiers . The Missouri State Guard , about 75 miles southwest of Lyon and under the command of Price , met with troops under Brig . Gen . Benjamin McCulloch near the end of July . The combined Confederate forces numbered about 12 , 000 , formed plans to attack Springfield , and marched northeast on July 31 . The armies met at dawn a few miles southwest of Springfield on the morning of August 10 in the Battle of Wilson ' s Creek . Lyon was wounded twice in the fighting ; shot in the head and leg and his horse shot from under him . He returned to Union lines and commandeered a bay horse ridden by Maj . E . L . McElhaney of the Missouri Infantry . Lyon , badly outnumbered by Confederate forces , then dramatically led a countercharge of the 2nd Kansas Infantry on Bloody Hill , where he was shot in the heart at about 9 : 30 am . Although the Union Army was defeated at Wilson ' s Creek , Lyon ' s quick action neutralized the effectiveness of pro - Southern forces in Missouri , allowing Union forces to secure the state . Fate of Lyon ' s remains . In the confused aftermath of the Union retreat from Wilson ' s Creek , Lyon ' s body was mistakenly left behind on the battlefield and discovered by Confederate forces . It was briefly buried on a Union soldier ' s farm outside Springfield until it could be returned to Lyon ' s relatives . Eventually the remains were interred at the family plot in Eastford , Connecticut , where an estimated crowd of 15 , 000 attended the funeral . A cenotaph stands in memory of Lyon in the Springfield National Cemetery , Missouri . Legacy . Lyon was slight of figure with a shabby appearance ; his boots were often unpolished , his uniform was often faded , and his insignia were often tarnished . Nonetheless , the men under his command were said to have respected him . Lyon was known for his love of mustard , and was often seen by his troops to be slathering it on thick slices of bread , even in the midst of battle . He never married ; it is often written that he bequeathed all his property to the federal government of the United States , but this is disputed . On December 24 , 1861 , the United States Congress passed a resolution of thanks for the " eminent and patriotic services of the late Brigadier General Nathaniel Lyon . The country to whose service he devoted his life will guard and preserve his fame as a part of its own glory . That the Thanks of Congress are hereby given to the brave officers who , under the command of the late general Lyon sustained the honor of the flag and achieved victory against overwhelming numbers at the battle of Springfield , Missouri . " Namesakes and honors . The 24th Missouri Volunteer Infantry was recruited as " The Lyon Legion " in honor of the General , and carried a unique regimental color , depicting a Lion beneath a constellation of six stars . Lyon County , Iowa , Lyon County , Kansas , Lyon County , Minnesota , Lyons Valley , Jamul , California and Lyon County , Nevada , are named in Nathaniel Lyon ' s honor . Two forts were also named in his honor : Fort Lyon in Colorado and Fort Lyon ( Virginia ) , which defended Washington , D . C . , during the American Civil War in Virginia . Lyon Park in St . Louis , Lyon Street in San Francisco and Lyon Lane in Carson City , Nevada are also named for him . General Nathaniel Lyon camped near Windsor Missouri ( Southwest of Kansas City ) in 1861 . The small settlement is almost abandoned now , but had a postmaster until 1901 . A water well still exists there which was dug by General Lyon ' s men and it reported that on Duck Creek one can still find graffiti carved in the rocks from 1861 .