On October 15 in New York, the U.S. Cavalry’s sole survivor from the 1876 battle known as Custer’s Last Stand will be auctioned during a Sotheby’s sale titled Custer’s Last Flag: The Culbertson Guidon from the Battle of the Little Bighorn (www.sothebys.com). The flag is being sold by the Detroit Institute of Arts, which acquired it in 1895 for $54. It is expected to fetch as much as $5 million. Army sergeant Ferdinand Culbertson found the flag three days after the battle, under a dead cavalryman. The relic’s condition is not mint; the guidon is bullet-scarred and torn and missing a star and a patch of stripes. Historians theorize that members of the burial party in which Culbertson served snipped the scraps for keeping as souvenirs.