Mankato was a member of the delegation who signed the Treaty with the Dakota on June 19, 1858. He appears (left) in the famous photograph of the treaty signers made at a photography studio in Washington, D.C. During the U.S.-Dakota War he led a band of Mdewakanton soldiers into battle at Fort Ridgely, Birch Coulee, and Wood Lake. On September 23, 1862, he was killed by a cannonball at the battle of Wood Lake.