Greenleaf was founded in 1858 by William Henry Greenleaf, Dana E. King, and Bennet M. and Judson A. Brink. The McGannons, Henry and John, also came in 1858. Greenleaf was platted on August 27, 1859 by William Greenleaf, who had come to Minnesota in 1858, and the township was named for or by him. When Greenleaf arrived, he immediately built a mill dam to power his flour and saw mills. Nearby Lake Willie was named after U. S. Willie, a lawyer who lived a year or two in Forest City and died there. A post office was established in Greenleaf in 1860 and he was legally appointed postmaster in 1861 and 1864. The post office remained in operation until it was discontinued in 1906. Greenleaf Lake was also named for William. Greenleaf was located within Ellsworth Township and Greenleaf Township. Ellsworth was named at the suggestion of Indian Uprising hero and the first “mayor” of Litchfield, Jesse V. Branham, Jr., who came to the area in 1857 along with George C. Whitcomb. Col. Elmer E. Ellsworth was the first Union officer killed in the Civil War in Alexandria, Virginia. He was a friend of Lincoln and when Lincon heard of Ellsworth's death, he said, “My boy! My boy! Was it necessary this sacrifice should be made?” Lincoln had Ellsworth's body brought to the White House to lay in state.