Military History The history of Fort Snelling, from its construction and activation in the 1820s until its decommissioning in 1946, reflects the development of the state of Minnesota and of the United States and its military endeavors over 120 years. The expansionist era (1805-1858) The Civil War (1861-1865) The battle flags of Minnesota The US-Dakota War of 1862 The fort expands (1865-1940) World War II (1941-1945) Fort Snelling National Cemetery