John A. Haydon (1830 – 1902) was a prominent American surveyor and civil engineer. As a self-taught civil engineer, Haydon made significant contributions to American railroading. Haydon's railroad career spanned the Baltimore and Ohio railroad expansion to the Ohio river in 1853 and several other railroads to the last transcontinental railroad, the Northern Pacific railway. Haydon led the 1872 Yellowstone River expedition, where he faced a Sioux Indian skirmish led by Sitting Bull, Red Cloud and Crazy Horse at the Battle of Pryor's Creek, Montana. He also served as a captain in the Confederate army Corps of Engineers under Generals Tilghman and Beauregard; captured at the battle of Fort Henry, early in the Civil War in 1862, he was paroled at Alton, South Carolina, in 1863 to serve the res