American Indian Wars: In Nebraska, 700 soldiers under United States General William S. Harney avenge the Grattan massacre by attacking a Sioux village and killing 100 men, women and children.

The American Indian Wars, also known as the American Frontier Wars, and the Indian Wars, were initially fought by European colonial empires, the United States, and briefly the Confederate States of America and Republic of Texas against various American Indian tribes in North America. These conflicts occurred from the time of the earliest colonial settlements in the 17th century until the end of the 19th century. The various conflicts resulted from a wide variety of factors, the most common being the desire of settlers and governments for tribal lands. The European powers and their colonies enlisted allied Indian tribes to help them conduct warfare against each other's colonial settlements. After the American Revolution, many conflicts were local to specific states or regions and frequently involved disputes over land use; many involved retaliatory violence.