Medicine Crow, 102, was the last Crow war chief as the result of his military accomplishments. He was awarded the Presidential Medal of Freedom, the highest honor awarded to a civilian in the United States, by President Barack Obama in 2009.
He was a teacher story teller, and tribal historian, a WWII veteran, and worked for the BIA.
Notice he has the title "Chief"? Unlike most people who use the title, his is genuine.
So how did he get the "war chief" designation?
LINK2 has more details of how he "counted coup" on his enemies making him eligible for the title "war chief", and and has more details of his life.
Joseph Medicine Crow became the last Plains Indian war chief ever after completing all four required tasks while fighting in Europe during World War II. These included touching an enemy soldier, stealing his weapon, leading a successful war party, and stealing an enemy’s horse.