Fort Abercrombie, in North Dakota, was an American fort established by authority of an act of Congress, March 3, 1857. The act allocated twenty-five square miles of land on the Red River in Dakota Territory to be used for a military outpost, but the exact location was left to the discretion of Lieutenant Colonel John J. Abercrombie. The fort was constructed in the year 1858. It was the first permanent military settlement in what became North Dakota, and is thus known as "The Gateway to the Dakotas".