Billings, Mont. ? After spending much of the last century in storage, the only U.S. flag not captured or lost during Custer’s Last Stand at the Battle of Little Bighorn sold at auction Friday for $2.2 million.

The buyer was identified by the New York auction house Sotheby’s as an American private collector.

Frayed, torn, and with possible bloodstains, the flag from one of America’s hallmark military engagements had been valued before its sale at up to $5 million.

The 7th U.S. Cavalry flag had been the property of the Detroit Institute of Arts. The museum paid just $54 for it in 1895.

“We’ll be using the (auction) proceeds to strengthen our collection of Native American art, which has a rather nice irony to it I think,” said the museum’s director, Graham Beal.

On June 25, 1876, Lt. Col. George Armstrong Custer and more than 200 troopers and scouts from the Crow Tribe were killed by up to 1,800 Lakota Sioux and Northern Cheyenne warriors near the Little Bighorn River.

Of the five guidons carried by Custer’s battalion only one was immediately recovered, from beneath the body of a fallen trooper.

According to testimonials from Indians involved in the fight, the trooper, Cpl. John Foley, was attempting to escape on horseback — and had almost succeeded — when he shot himself in the head.

All the other flags under Custer’s command were believed captured by the victorious Indians.

The recovered flag later became known as the Culbertson Guidon, after the member of the burial party who recovered it, Sgt. Ferdinand Culbertson. Made of silk, it measures 33 inches by 27 inches, and features 34 gold stars.