Fort Berthold was two sequential forts on the Missouri River in North Dakota, both of which began as fur trading posts. The second became a post for the U. S. Army and later became the Indian Agency for the Arikara, Hidatsa, and Mandan tribes. The sites are both now under Lake Sakakawea.
The forts were named after Italian-born Bartholomew Berthold (1780-1831), prominent merchant, then fur trader of St. Louis with the Chouteau and Astor families. The Berthold mansion, headquarters for pro-Southern secessionists in 1861, was also referred to as "Fort Berthold".
The first Fort Berthold, was an American Fur Company post on the Missouri River founded in 1845. It was originally called Fort James until it was renamed in 1846. It was burned by the Sioux in 1862, as a consequence of the hostilities of the Dakota War of 1862.
The second Fort Berthold, began as Fort Atkinson, an independent fur trade post built by Charles Larpenteur on the Missouri River in 1858, south of what is now White Shield, North Dakota. Following the destruction of the first Fort Berthold, the American Fur Company purchased Fort Atkinson in 1862 and renamed it Fort Berthold. During the campaigns of the Union Army against the Sioux, the Army left a garrison there and built a log camp outside the fur trading post stockade during the winter of 1864 - 1865. It remained an army post until 1867, when the military garrison removed to Fort Stevenson.
Like many forts in the West it came into the possession of the Department of Interior, from 1868 the post became the Indian Agency for the Arikara, Hidatsa, and Mandan tribes, now the Fort Berthold Indian Reservation and continued to function as a trading post to 1874. The site is now under the waters of Lake Sakakawea created by the Garrison Dam in 1953.
- Berthold, Bartholomew (1780-1831). Berthold family papers (1785-1954.) http://collections.mohistory.org/archive/ARC:A0119
- Fort Berthold Reservation in 1950 from Discovering Lewis & Clark ®, http://www.lewis-clark.org © 1998-2009 VIAs Inc. © 2009 by The Lewis and Clark Fort Mandan Foundation, Washburn, North Dakota. Includes a map showing the land flooded by the Lake Sakakawea reservoir and the locastion of flooded towns, homes and Fort Berthold.
- North American Forts; West: Fort Berthold
- Fort Berthold Site From Discovering Lewis & Clark ®, http://www.lewis-clark.org © 1998-2009 VIAs Inc. © 2009 by The Lewis and Clark Fort Mandan Foundation, Washburn, North Dakota. Including Fort Berthold's early history and a photo of Old Fort Berthold, Dakota Territory, in 1864.