A historical marker that tells about a Union Army officer who led a mass prison escape will be dedicated Saturday in Morgantown, where he was murdered in 1895. The marker tells the story of Maj. Andrew Graff Hamilton of Pennsylvania. The Kentucky Historical Society says Hamilton joined Company A of the 12th Kentucky Cavalry in 1862 and was captured at Jonesboro, Tennessee, a year later and sent to Libby Prison in Richmond, Virginia. Hamilton and Colonel Thomas Rose led the escape of 109 Union officers in 1864, but Rose and 47 others were recaptured. Hamilton is buried in the Bethlehem Cemetery in Reedyville. The dedication will be Saturday morning at the Butler County Courthouse.