St. Louis Arsenal facts for kids

The St. Louis Arsenal is a large group of buildings in St. Louis, Missouri. It's like a big storage place for military weapons and ammunition. Today, the United States Air Force uses and takes care of it. During the American Civil War, a Union Army captain named Nathaniel Lyon moved many weapons from this arsenal to Illinois. This action caused more tension between people who wanted to leave the United States (secessionists) and those who wanted to stay loyal to the government.
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The St. Louis Arsenal: Its Start and Early Years
In 1827, the United States Department of War decided to build a new, bigger arsenal. The old one, Fort Belle Fontaine, was 22 years old and too small for the growing military in the West. Lieutenant Martin Thomas chose a 37-acre piece of land next to the Mississippi River for the new arsenal. This spot was good because it was near the main military base, Jefferson Barracks Military Post, and easy to reach by city and river.
By 1840, there were 22 buildings at the arsenal. About 30 soldiers and 30 civilian workers were there. The workers put together weapons and artillery (large guns) from parts made by other companies. The arsenal originally included an island in the Mississippi River, but that island is now gone.
Helping Out in the Mexican-American War
When the Mexican–American War started, the army needed many more weapons and ammunition. At its busiest during the war, the St. Louis Arsenal had over 500 civilian workers. In just two years, they made a huge amount of supplies. This included 19,500 artillery rounds, 8.4 million small gun cartridges, and many other weapons. After the war, production slowed down. The workers then spent time fixing and cleaning weapons that came back from the war.
Supporting Troops in the Utah War
The arsenal became busy again in 1857 and 1858 during the Utah War. President James Buchanan sent troops to deal with conflicts involving Mormons. More than 100 workers were employed at the arsenal. They provided many weapons for the forces led by William S. Harney.
The Civil War and the Arsenal's Role
Before the Civil War began, some Southern states asked for their share of weapons from the St. Louis Arsenal. They wanted these weapons sent to their own state armories. The Secretary of War, John B. Floyd, was accused of helping with this. He resigned in December 1860. Even though an investigation cleared him, many people thought he had helped arm the Confederate States of America before the war officially started.
The St. Louis Arsenal was very important. It was used for putting weapons together, not making them from scratch. It had the largest collection of rifles and muskets among the states that allowed slavery. It was also the third largest place for arms and ammunition in the Federal system. Despite its importance, it usually had only about 40 military and civilian staff guarding it.
Missouri's Neutrality and the Arsenal
In March 1861, the Missouri Constitutional Convention of 1861–1863 voted to stay in the Union. However, they also decided not to give weapons or soldiers to either side if a war broke out. This made the security of the large arsenal a big concern right away.
On April 20, 1861, a group of people who supported the Confederacy took over the only other arsenal in Missouri, the Liberty Arsenal. They stole about 1,000 rifles and muskets.
Captain Lyon Takes Action
On April 23, Brigadier General Harney left for Washington. This left Captain Lyon in charge of the Western Department and the St. Louis Arsenal temporarily. Lyon immediately started signing up Missouri volunteers who supported the Union to join the Federal army. The Secretary of War, Simon Cameron, had ordered this a week earlier, but General Harney had refused to do it.
Cameron, General-in-Chief Winfield Scott, and Union supporters in the Midwest were worried about the more than 30,000 weapons at the arsenal. So, on the night of April 29, Captain Nathaniel Lyon moved 21,000 rifles and muskets to Alton, Illinois, using a steamboat. This was done on orders from Secretary Cameron.
The Camp Jackson Incident
Around May 1, Missouri Governor Claiborne Fox Jackson called out the Missouri Volunteer Militia for "maneuvers." These exercises took place about 4.5 miles northwest of the arsenal at Lindell's Grove. Governor Jackson favored the South but had publicly promised Missouri would stay neutral.
Lyon suspected these maneuvers were a secret plan to take over the arsenal. His suspicions grew when he found out that Jefferson Davis, the Confederate President, had sent artillery to the maneuvers.
On May 10, Lyon surrounded the militia, and they surrendered. As the soldiers marched the militiamen through the streets of St. Louis back to the arsenal, a riot broke out. The troops fired into the crowd, killing 28 people and wounding 90. Seven more people died later that night. This event is known as the Camp Jackson affair.
The Price-Harney Truce
On May 11, the Missouri General Assembly created the Missouri State Guard. This group was meant to "resist invasion" by federal forces and "suppress rebellion" by Missouri Unionists. Sterling Price was made its major general.
On May 12, General Price and General William S. Harney signed the Price–Harney Truce. This agreement promised that state and federal forces would keep order, protect people's rights, and avoid causing trouble. Price told Harney he would keep Missouri in the Union and fight Confederate forces if they entered the state.
However, Price's statement was likely a trick to gain time. At that very moment, Governor Jackson had secretly sent people to ask Confederate President Jefferson Davis to invade Missouri. They told Davis that the Missouri State Guard would fight with the Confederate troops to drive the Federal forces out of the state.
On May 30, Abraham Lincoln removed Harney from command. Missouri Unionists had demanded this because they felt Harney was letting Governor Jackson and General Price build an army that would eventually attack St. Louis, the main Union stronghold in the state.
War Breaks Out in Missouri
On June 11, Lyon and Jackson met one last time in St. Louis. They talked about whether Federal troops could move freely inside the state. Jackson demanded that Federal forces stay only in St. Louis and that pro-Union "Home Guard" groups be disbanded. Lyon replied that limiting Federal authority "means war." The meeting ended.
Jackson and General Price immediately went back to Jefferson City. They ordered railroad bridges to be burned and got ready for war. Lyon followed a few days later, moving troops and artillery up the Missouri River by steamboat. He captured the state capital without a fight. Then, he defeated the Missouri State Guard at the Battle of Boonville on June 17, 1861. This action helped the Federal Government control most of the important parts of Missouri for the rest of the war.
Lyon chased Governor Jackson and the State Guard toward the Arkansas border. In August, Lyon's troops were facing a much larger combined force of Missouri State Guard, Confederates, and Arkansas State Troops. Lyon had to attack first, south of Springfield. The Battle of Wilson's Creek, sometimes called the "Bull Run of the West," was confusing and bloody. General Lyon was killed leading a charge late in the day. His replacement, Major Schofield, pulled back toward Springfield because they were low on ammunition. The tired Southern army did not chase them.
Even though Wilson's Creek was a victory for the Confederates, it didn't change the overall war much. The Arkansas and Confederate troops went back across the border, leaving Sterling Price to try and "liberate" Missouri on his own. Price won some battles, but he eventually had to pull back too, because he didn't have enough supplies.
The St. Louis Arsenal stayed under Federal control throughout the Civil War. With St. Louis firmly in Union hands, the arsenal provided many war supplies to the armies fighting in the Western Theater.
Moving the Arsenal to Jefferson Barracks
In March 1869, 10 acres of the old arsenal grounds were given to the City of St. Louis. This land became Lyon Park, named after Captain Nathaniel Lyon.
In 1871, the arsenal was moved to the more secure Jefferson Barracks Military Post. The U.S. Army kept this complex. It was used a lot for storing and giving out weapons and ammunition during World War I and World War II. In 1956, the arsenal was transferred to the United States Air Force.
The Arsenal Today
The St. Louis Arsenal complex is still an active part of the military today. Much of it is off-limits to tourists and visitors. The United States Air Force and the United States Department of Defense maintain the arsenal. It houses a major branch of the National Geospatial-Intelligence Agency, which deals with maps and satellite images for national security.