The United States government did not enforce the treaty restriction against unauthorized settlement. Lakota and other bands attacked settlers and even emigrant trains, causing public pressure on the U.S. Army to punish the hostiles. On September 3, 1855, 700 soldiers under U.S. General William S. Harney avenged the Grattan Massacre by attacking a Lakota village in Nebraska, killing about 100 men, women, and children. A series of short "wars" followed, and in 1862–1864, as refugees from the "Dakota War of 1862" in Minnesota fled west to their allies in Montana and Dakota Territory. Increasing illegal settlement after the American Civil War caused war once again.