— the largest stockpile in any slave state. Initial Unionist actions Missouri was within the Department of the West, a geographical command of the United States Army commanded by Brigadier General William S. Harney, with its headquarters at Jefferson Barracks in St. Louis. Harney, an elderly career officer, wished to avoid open conflict with secessionist forces. On April 23, the War Department replaced Harney with Captain Nathaniel Lyon as acting commander. Lyon, a passionate Unionist, immediately began enlisting and arming St. Louis Unionists as home guard "Missouri Volunteers", an action previously ordered by the Secretary of War but not acted upon by Harney. Most of Lyon's early recruits were "Forty-Eighters" and "Wide Awakes" (a marching society formed during the 1860 election by the Republican Party). According to one estimate, 80% of the volunteers in the first Missouri Volunteer regiments were German-American immigrants. Pro-slavery native-born Missourians prejudicially targeted the anti-slavery foreign-born Germans. By order of the War Department, Lyon's next action was to move the arms held in the St. Louis Arsenal out of reach of Missouri secessionists. Early in the morning of April 26, 1861, nearly 21,000 rifles were loaded on the steamer City of Alton, which carried them across the Mississippi River to Illinois. The remainder were held for issue to Lyon's Missouri Volunteers. Secessionist actions Missouri Governor Claiborne Fox Jackson had been elected in 1860 on the ticket of the pro-Union Douglas faction of the Democratic Party, but privately supported secession. Since the Constitutional Convention had voted against secession, Jackson and his fellow secessionists decided to carry it out by seizing St. Louis by force and presenting the people of Missouri with a fait accompli. The most significant obstacle was the St. Louis Arsenal, which was heavily fortified with thick walls. In mid-April 1861, Jackson wrote to Confederate President Jefferson Davis, asking for heavy artillery to breach the walls of the arsenal. His letter was carried by militia officers Colton Green and Basil Wilson Duke. Around May 1, Jackson called out part of the Missouri Volunteer Militia for "maneuvers" near St. Louis, under the command of Brigadier General Daniel M. Frost. The militia set up "Camp Jackson", about northwest of the arsenal. The campsite was located at Lindell's Grove (then outside the city of St. Louis, and today part of the campus of St. Louis University on Lindell Boulevard). Davis agreed to Jackson's request. On May 9, the