LAME DEER — For 1,000 years or more, native peoples have etched their histories and prophecies on the sandstone faces of Deer Medicine Rocks near what is now Lame Deer. Barely visible bighorn sheep, warriors on horseback and a grizzly bear roam the soft, sheer faces of the rock outcrop just off the Northern Cheyenne Reservation. And on an early June day 136 years ago, a Sioux artist carved a vision that had come to Hunkpapa medicine man Sitting Bull after a torturous Sundance ceremony. In the dream, soldiers with “grasshopper” legs fell from the sky into the Indian camp....