In 1903, the National Police Gazette wrote that Irish boxers were greeted by audiences with "a hearty cheer and earnest backing." For a time in the United States, the Irishman became the idealized boxer--the apotheosis of masculinity. The "Emperors of Masculinity," as author Gerard Earley described the leading heavyweight boxers of the era, had become Emerald Emperors. This book is the first in-depth study of the role played by the Irish and Irish Americans in U.S. boxing. It examines the lives of many men who contributed to the sport's development and looks at social, cultural, and historical facets of their lives and careers. It is a story of assimilation, achievement, and heartbreak in the most brutal sport of all.