Career
He was among the 31 soldiers who received the Medal of Honor for during General Nelson A. Miles "winter campaign" against the Sioux Indians in the Montana Territory between October 1876 and January 1877. Born in Wexford, Ireland in 1833, Denis Byrne emigrated to the United States where he settled in New York City. He eventually enlisted in the United States. Army and was sent to the frontier to serve with 5th United States. By the start of General Nelson A. Miles "winter campaign" against the Sioux Indians in the Montana Territory, Byrne had become a veteran Indian fighter and reached the rank of sergeant.
Between October 1876 and January 1877, he participated in many battles against the Sioux, most notably, against Chief Sitting Bulletin at Cedar Creek.
He and 31 other soldiers were received the Medal of Honor for "gallantry in engagements" with the Sioux at Cedar Creek and other actions. He died at Bird Island, Minnesota on December 31, 1905, at age 72.