On 15 September, about 3,500 men of the Missouri State Guard plus a number of irregulars from St. Joseph set out for Lexington. In the evening, Price sent ex-Senator and now General David Rice Atchison from Lexington to help these men, mostly new recruits, cross the river near Liberty.
Union troops of the 16th Illinois Infantry and the 39th Ohio regiments were guarding the Platte River railroad bridge in Buchanan County, which had earlier been sabotaged in the Platte Bridge Railroad Tragedy. These troops started moving to Liberty. At the same time, Union Lt. Col. John Scott led a small force (500 men of the 3rd Iowa Infantry, about 70 Missouri Home Guards, and one 6-pound smoothbore cannon) from guarding the railroad at Cameron towards Liberty. Heavy rain and bad roads limited his progress to only seven miles that day. On 16 September, Scott camped in Centreville (ten miles north of Liberty), where he heard artillery fire in the distance.
General Atchison, who had lived in Liberty, deployed his men in the brush on either side of the Missouri River bottom land road leading to the landing. At about 3:00 P.M., Scott's troops encountered the State Guard pickets and were attacked from both sides.
Scott's artillerymen fired two rounds of canister, inflicting heavy damage. However, a fresh volley from the State Guards scattered or killed most of the gunners. Scott ordered his outnumbered force to fall back to the bluffs in Liberty, hauling off the gun by hand. Atchison attempted a flanking movement on the Federal right, which resulted in a sharp fight. The Union force continued to withdraw, firing as they retreated, taking with them nearly all their wounded, but abandoning their ammunition wagon and a caisson. The State Guard pursued for some distance, but Atchison did not press the attack.
Just before nightfall, Scott's force retired to Liberty, entering the town about an hour after sunset. Atchison and the State Guards from northern Missouri crossed the river to reinforce Price in his successful attack on Lexington. After sunset the Union troops returned to retrieve their dead from the field.
Union troops set up a hospital on the campus of William Jewell College in Liberty and buried their dead on the campus.