Charles Albert Varnum received a Medal of Honor for his role in a conflict at Drexel Mission following a massacre that occured on what Indian reservation?
Charles Varnum:  He was most noted as the commander of the scouts for George Armstrong Custer in the Little Bighorn Campaign (of which he was the last of the surviving officers to die of natural causes) during the Great Sioux War, as well as receiving the Medal of Honor for his actions in a conflict at Drexel Mission following the Wounded Knee Massacre. Wounded Knee Massacre: The Wounded Knee Massacre (also called the Battle of Wounded Knee) occurred on December 29, 1890, near Wounded Knee Creek (Lakota: "Čhaŋkpé Ópi Wakpála") on the Lakota Pine Ridge Indian Reservation in the U.S. state of South Dakota.
Lakota Pine Ridge Indian Reservation