The Battle of Lone Jack took place during the American Civil War on August 15–16, 1862 in Jackson County, Missouri.

[1] On August 15, 1862 Union Major Emory S. Foster, under orders from Totten, led a 740-man combined force from Lexington to Lone Jack.

Upon reaching the Lone Jack area, Foster received intelligence that 1,600 rebels under Col. Coffee and Lt. Col. Tracy were camped near town and prepared to attack them.

The estimate of the rebel command was revised down to only 800 and at about 11:00 p.m., Foster and his men attacked the Confederate camp and dispersed the enemy.

Colonel Cockrell conferred with Upton Hays, Lt. Col. Sidney D. Jackman, and DeWitt C. Hunter and determined to give battle the next morning with the intent of overwhelming the much smaller Union force.

[1] Cockrell's plan was to clandestinely deploy Hunter, Jackman and Tracy's forces in a field to the west of town well before sunrise on August 16 and await the opening of the fight.

[3] With sunrise exposing them while awaiting Hays' tardy advance, Jackman, Hunter, and Tracy attacked but were held in check.

Union Captain Long's 2nd Battalion Missouri State Militia Cavalry concealed behind a hedge row of Osage orange trees poured a crossfire on the Confederates, temporarily repulsing them.

[4] On the other side of the field Hunter's force was stalled by three companies of Captain Plumb's 6th Missouri State Militia Cavalry.

Much of the fighting then devolved into a war of attrition between Confederates on the western side of the street, Union men on the right with their artillery in the middle.

Excluded from Hunter's total were an unknown number of dead Confederates claimed by their friends and families for burial elsewhere.

Elkins was to say that he disgusted of war after what he witnessed in the battle:[11] Confederate guerrilla and later outlaw leader Thomas Coleman Younger was notable for his actions at Lone Jack.

[14] In the 1969 movie True Grit, character Rooster Cogburn (played by John Wayne) tells Mattie Ross that he lost an eye at the Battle of Lone Jack, calling it "a scrap outside of Kansas City.