The Shawnee and the Kansas Indians were the first human inhabitants of Johnson County, KS. During that time the indians could find shelter by the streams, and Kansas was home to bears, beavers, mink, otters, and wolves. In 1825, the Shawnee reservation was set aside for these Indians in accordance with a treaty. By May, 1844, the reservation contained more than 1,600,000 acres.
The county was officially established in 1855. The first election in the Kansas Territory was held in 1853. in the first election whites and Indians voted, even though the indians were not legal Uninted States citizens. People from Johnson County were not represented at the first Free State Convention because they were to pro-slavery. The legislature of Kansas was summoned to Topeka on July 4th, 1856, but was dismissed by colonel Edwin V. Sumner on the orders of the president of the Uninted States. In August of that year a party of border ruffians went to the Quaker Mission, threatened the superintendent, and stole 6 horses, a mule, and a wagon. A few days prior to his trial a young Missourian named Cantral, participated in the battle of blackjack under the command of John Brown. He fought on the free state side. he was captured by a group of border ruffians and was later executed for treason against Missouri. One of the most horrid murders commited during the border war was the murder of Major Gay, U.S. He was shot because he said he agreed with the ideas of the free staters.
A major battle of the border war also known as "Bleeding Kansas" was what has come to be known as "The Battle of Bull Creek." General Lane met Gen. Reid who was commanding the the pro-slavery forces. Lane's forces numbered about 400, while Reid's numbered about 1,500. A few shots were exchanged by skirmishers on both sides and Reid ordered his men to fall back. They went all the way to Westport, MO. They stopped and burned the house of a free stater along the way in retaliation. When the Civil War began, Johnson County gathered its full quota of soldiers. The first battle of the Civil War to take place within the borders of the county was the battle of Blow-hard. It took place in August 1861. C.R. Jennison made a raid on Olathe after the battle of Blow-hard. Quantrill made a famous raid on Olathe where he and his men stole valuables and horses, as well as killed several civilians. Later, this type of raid was tried again at Shawnee. Nearly the entire city was burned down.