of the four general officers in the regular army at the time, (alongside the War of 1812 veterans Winfield Scott, John Wool, and David Twiggs, the next-youngest, at 70, because of the lack of a fixed retirement age). American Civil War As the American Civil War began, Harney was still in command of the Army's Department of the West based at Jefferson Barracks in St. Louis, Missouri, and his wife's family was prominent in the area. General Twiggs accepted a Confederate commission to head the Department of Louisiana and was accordingly dismissed from the US Army and replaced by Edwin V. Sumner. Missouri Governor Claiborne Jackson was pro-secession, but the majority of Missourians favored Union. After the bombardment of Fort Sumter, President Abraham Lincoln called for troops to suppress the rebellion. Jackson refused and began plotting with Confederate authorities to bring about Missouri's secession by a military coup. On May 10, 1861, Captain Nathaniel Lyon, commander of the St. Louis Arsenal, led a force of unofficial Unionist "Home Guards" to capture a force of state militia that were poised to seize the Arsenal by acting without any authorization from Harney, his superior. The Camp Jackson Affair resulted in a bloody riot in St. Louis, which horrified Harney. The state legislature responded by reorganizing the militia as the Missouri State Guard and authorizing it to resist an invasion by federal troops. Harney tried to calm the situation and agreed to the Price–Harney Truce with Guard Commander Sterling Price, who was married to Harney's wife's niece. They agreed that the State Guard would control most of Missouri while federal troops stayed near St. Louis. The deal also involved Missouri Governor Claiborne Jackson, who favored secession but swore allegiance to the Union. That was not acceptable to Unionist leaders in Missouri, including the Republican leader Francis Preston Blair, Jr., since Price did nothing to prevent the organization of pro-Confederate forces or to protect Unionists in his territory. Worsening matters was Harney's Tennessee heritage, which made his loyalty to the Union suspect. Blair reported all to the Lincoln administration in Washington, DC, and was authorized to replace Harney with Lyon, which Blair did on 30 May. Recalled to Washington to discuss the situation, Harney was captured by Confederates at Harper's Ferry on April 25, 1861. He was offered a command by Confederate General Robert E. Lee but turned down the offer. However, because he