Fort Ridgely, completed in 1855, chiefly helped the federal government manage the transfer of land ownership from American Indians to increasing numbers of European immigrant farmers, a role that did not imply the need for a defensive stockade. When the six-week U.S.-Dakota War began in August 1862, however, it became the only military post in the area and took on great importance. On August 20 and 22, 1862, as many as 400 Dakota warriors attacked the fort, which was defended by only 280 soldiers and refugees. Artillery offset the lack of a stockade and the fort's vulnerable location, forcing Dakota forces to withdraw. Before the events that led to war in 1862, soldiers at Fort Ridgely endured loneliness and boredom, with records noting complaints about housekeeping duties and severe winters. After the Civil War began in 1861, Minnesota citizen soldiers replaced regular Army troops needed in the South, and when the U.S.-Dakota War erupted in 1862, those volunteers were among the first to respond and the first to die in combat. Hundreds of European immigrant families fled to Fort Ridgely for protection. The U.S. military left the fort in 1872, and most of its buildings decayed or were adapted to other uses. A battle monument was erected in 1896, Fort Ridgely State Park was created in 1911, excavations in 1935 uncovered eight building foundations, and the fort's stone commissary was preserved and now serves as a visitor center.