Spear Spencer served in the Kentucky "Corn Stalk" Militia from 1792 to 1801 and took part in the St. Clair and Wayne Indian campaigns. In 1809 he was captain of militia of Harrison County, Indiana, and he formed Spencer's "Yellow Jackets," which joined Gen. Wm. Henry Harrison's command in the Tippecanoe campaign in the upper Wabash Valley. Spencer was killed in battle on Nov. 7, 1811. In 1824, the county was named for him from parts of Nelson, Shelby, and Bullitt counties.