I think that you are probably mistaken. Brian Boru probably fought and commanded his armies on campaigns well into old age. But Wikipedia gives his birth year as about 941 and his death as 23 April 1014, making him about 73 years, give or take a few years, when he was killed at the Battle of Clontarf.brian boru was 80 when he defeated a viking invasion
Brian Boru - WikipediaThere are many accounts of how Brian was killed, from dying in heroic man-to-man combat to being killed by the fleeing Viking mercenary Brodir while praying in his tent at Clontarf. After his death, his body was taken to Swords, Co. Dublin for the wake and then to Armagh to be buried. His tomb is said to be in the north wall of St Patrick's Cathedral in the city of Armagh.
Crowheart, Wyoming - WikipediaNearby Crowheart Butte was the site of a battle between the Crow and Shoshone American Indian tribes in 1866. According to legend, following a five-day battle for rights to the hunting grounds in the Wind River Range, Chief Washakie of the Shoshone and Chief Big Robber of the Crow agreed to a duel, with the winner gaining the rights to the Wind River hunting grounds. Chief Washakie eventually prevailed, but he was so impressed with the courage of his opponent, that rather than scalp him, he instead cut out his heart and placed it on the end of his lance.
Nana (chief) - WikipediaNana, now almost 80 years old (according to some reports, nearly 90-years), formed his own war party with the Chihenne (Warm Springs Apache), enlisting loitering warriors in the reservations. His band joined by 15 Tsokanende, 12 Mescalero warriors and a couple of Navajo, plus women and children, began raiding Army supply trains and isolated settlers. In less than a month Nana fought seven or eight battles stretching over the course of 1,000 miles and killed 30-40 Americans, at least as many Mexicans, captured about 200 horses to replace 100 ridden to death and then fled back to Mexico.:174–177 He and his small force, evaded more than 1,000 soldiers, 300-400 civilian militia volunteers and Apache and Navajo Indian Scouts.