The engagement was over in less than an hour.

All 81 men were killed.

The Fetterman Fight, as it became known, was the single largest loss of American soldiers to Indigenous forces between the Battle of the Little Bighorn and the various massacres during the Great Sioux War of 1876.

In the context of the Civil War, whose bloodiest battles had killed thousands in a day, the number 81 might seem modest.

But the psychological shock of the destruction of an entire command — 81 men setting out and not one returning — was enormous.