During this decade, Roman Nose and his fellow Dog Soldiers planned an attack against Captain Nicholas J. O'Brien in the Battle of Julesburg. The Battles of Stony Lake and Wood Lake occurred during a war in this decade in which Alexander Ramsey faced off against Shakopee and Big Eagle. During this decade, the largest penal mass execution in U.S. history included the deaths of (*) 38 American Indians (10[1])who were hanged at Mankato. The Treaty of Fort Laramie concluded a war in this decade named for Oglala Lakota chief Red Cloud. (-5[2])In this decade, the Dakota War occurred at the same time as a war in which the Chickasaw and Choctaw fought in the Battles of Perryville and Pea Ridge. Dozens of Cheyenne and Arapaho were killed in the Sand Creek Massacre during, for 10 points, what decade during which some Sioux fought in the Civil War? (10[1])■END■ (10[2])