Charles Eugene Flandrau (1828-1903) was an American lawyer and colonel in the Union Army. In 1853, he relocated to Traverse des Sioux, Minnesota to practice law. During the 1850s, he served on the Territorial Council of Minnesota, in the Minnesota Constitutional Convention, and on the territorial and state supreme courts. He was also appointed U. S. Agent for the Sioux in 1856. In 1862, learning of a violent Lakota uprising in the southwestern corner of the state, he enlisted in the Union Army as a captain, and assembled an armed force to rush to the defense of the community of New Ulm. It is in honour of his success there that both Flandrau State Park and the community of Flandreau, South Dakota are so named. In 1867, he was the Democratic candidate for governor but was defeated by William Rainey Marshall. In 1869 he ran for chief justice of the Minnesota supreme court, but was again defeated.