Tolan saw action in the Montana Territory during the Great Sioux War of 1876-77 and, on June 25, 1876, was present at the Battle of the Little Bighorn against Chief Sitting Bull and the Sioux. A member of Company D under Captain Thomas Weir, he and several other soldiers volunteered to carry water from the Little Bighorn River to wounded soldiers at the Reno-Benteen site under a most galling fire. He and the other Little Bighorn water carriers were among the twenty-two soldiers recommended for the Medal of Honor, Tolan officially receiving his award on October 5, 1878.>