Prior to the American Civil War, Lexington was an agricultural town of over 4,000 residents that served as the
county seat of Lafayette County and enjoyed a position of considerable local importance on the
Missouri River in west-central Missouri.
Hemp (used for rope production),
tobacco,
coal and
cattle all contributed to the town's wealth, as did the river trade. Though Missouri remained in the Union during the war, many of Lexington's residents were slaveowners, and several openly sympathized with the Southern aim of preserving slavery. Lafayette County had a high ratio of slaves to free persons, with slaves comprising 32% of its population. Following the
Battle of Boonville in June 1861, Federal Brigadier General
Nathaniel Lyon ordered the 5th Regiment of the United States Reserve Corps to occupy Lexington. This regiment was composed primarily of Germans from
St. Louis, and it had participated in the
Camp Jackson Affair. Arriving on the steamer
White Cloud on July 9, the Northerners were commanded by
Colonel Charles G. Stifel. Stifel's second in command was Lieutenant Colonel Robert White, who became a primary point of contact with the local civilians. Stifel selected the defunct Masonic College in Lexington as his headquarters, and the soldiers began entrenching and fortifying that position. Stifel's scouts began securing or destroying boats that could be used to cross the river, and also confiscated about 200 kegs of gunpowder, 33 muskets, and two 6-pounder cannons from the area. The cannons were placed under the command of Charles M. Pirner. Several local pro-Union
home guard companies were raised and placed under the command of Major Frederick W. Becker. In mid-August the 90-day enlistments of Stifel's regiment were expiring, and they were ordered to return to St. Louis. White had been organizing a new regiment locally, but he suddenly left for several weeks during which time Major Becker had command of the post. Meanwhile, on the Southern side, self-styled Colonel
Henry L. Routt of Clay County had collected around a thousand men for a regiment that he was raising. Routt had led the force that had seized the
Liberty Arsenal in April. Routt now arrested several prominent Union men, including former Missouri governor
Austin A. King, then surrounded the Federal outpost at Lexington. He demanded Becker's surrender but this was refused. One night two of Becker's men, Charles and Gustave Pirner, tested some rounds they had fabricated for two mortars that had come into their possession. They lobbed three shells into Routt's encampment with one of the mortars, causing a panic but no real damage. Later, learning of the approach of Colonel Thomas A. Marshall's 1st Illinois cavalry, Routt withdrew from the area. White returned at the end of August and briefly assumed command of the post from Becker until the Illinois cavalry arrived a few days later. White resumed organization of the 14th Home Guard Regiment. Following their victory at
Wilson's Creek on August 10, the main body of the pro-Confederate Missouri State Guard under Major General
Sterling Price marched toward the Missouri-Kansas border with around 7,000 men to repel incursions by Lane's pro-Union Kansas Brigade. On September 2, the Guard drove away Lane's Kansans in the
Battle of Dry Wood Creek, sending them back beyond
Fort Scott. Price then turned north along the border and toward Lexington, intending to break Federal control of the Missouri River and gather recruits from both sides of the river. Price collected recruits as he went along, including Routt and several hundred of his men then at the town of Index in
Cass County. Federal reinforcements arrived in Lexington on September 4: the 13th Missouri Infantry commanded by Colonel
Everett Peabody and a battalion of the United States Reserve Corps under Major
Robert T. Van Horn. To prevent rebel Governor
Claiborne Fox Jackson from obtaining any funds from local banks, General
John C. Frémont gave orders to impound their funds. On September 7, Marshall removed approximately $1,000,000 from the Farmers' Bank in Lexington while Peabody was dispatched to
Warrensburg to do the same there. On arriving in Warrensburg, Peabody's detachment found itself in Price's path and made a hasty retreat back to Lexington. Finally, on September 10, Colonel
James A. Mulligan arrived to take command with his
23rd Illinois Volunteer Infantry Regiment—known as the "Irish Brigade"—and a detachment of the 27th Missouri Mounted Infantry under Lieutenant Colonel Benjamin W. Grover. On September 11, the 13th Missouri Infantry and Van Horn's battalion returned to Lexington. Trees were felled to make lines of fire, and earthworks were erected around the dormitory and classroom buildings. His superiors dispatched further reinforcements under
Samuel D. Sturgis, with which Mulligan hoped to hold his enlarged position, but they were ambushed by pro-Confederate militia (alerted by a secessionist telegraph tapper) and compelled to retreat. ==Battle==