During their exploration of the Missouri and Columbia Rivers, Lewis and Clark held councils with the Ponca, Omaha, and Sioux Indians inhabiting this region. The council with the Sioux occurred August 28-31, 1804, at Calumet Bluff, now the southern abutment of Gavins Point Dam. By 1857, the Ponca and Omaha tribes had signed peace treaties and had been removed to reservations, but peaceful relations with the Sioux were still some years distant. In 1862-1863, General Alfred Sully, provisioned by steamboat, campaigned against the Sioux in Dakota Territory. Many local inhabitants took part in the expedition as members of the Second Regiment, Nebraska Volunteer Cavalry, leaving the Northern Nebraska settlements unprotected. On July 23, 1863, Indians, alleged to be Sioux, invaded the area, killing the children of Henson Wiseman who lived near present-day Wynot, Nebraska.