He, two brothers, and his sister Mary Greyeyes enlisted in the Canadian Army during the Second World War. Greyeyes Steele taught advanced weaponry for two years before returning to Canada to qualify as an officer. He was the first Status Indian to achieve such a commission overseas. He was then assigned to the Saskatoon Light Infantry (Machine Gun) and commanded a mortar platoon in the Italian Campaign. He was awarded the Greek War Cross for his support of the 3rd Greek Mountain Brigade in the Battle of Rimini (1944). After VE Day he served as an intelligence officer with the Royal Winnipeg Rifles during the occupation of Germany. He played soccer in the 1946 Inter-Allied Games.