Fort Sisseton (originally called Fort Wadsworth) was established by Major John Clowney, 30th Wisconsin Volunteer Infantry on August 1, 1864. Clowney, a Mexican War Veteran was pre-war carpenter and builder. He was selected to superintend the construction of the new fort by Brigadier General Henry H. Sibley. The Fort was designed to support four 100 man companies. The first structures were of logs. The permanent buildings were constructed of brick and stone.

Major Clowney’s original garrison consisted of Companies B,E,K, 30th Wisconsin, Company M, 2nd Minnesota Cavalry and a section of the 3rd Minnesota Battery. The garrison was reinforced on September 1, 1864 by company G, 30th Wisconsin. In October, 1864 the 30th Wisconsin was sent to Kentucky and was replaced at Fort Wadsworth by four Companies of the 2nd Minnesota Cavalry.

The Volunteers continued the construction of the fort until June 8, 1866, when they were relieved by Companies C,K,E,G, 10th United States Infantry under Major Samuel B. Hayman. The Garrisoned and improved the fort until it was abandoned on June 1, 1889.

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