The Cimarron Redoubt (also known as the Deep Hole Redoubt) was an improvised U.S. Army fortification south of the city of Ashland in Clark County, Kansas, United States. Built in 1870 near a major trade route's crossing of the Cimarron River, it was later used for a variety of civilian purposes, including a post office. Today, it lies abandoned amid farm fields in southern Center Township.