Fred "Duke" Slater was the greatest African American football player of the first half of the 20th century. Born into poverty, he developed into a two-time All-American tackle at the University of Iowa from 1918 to 1921. When the College Football Hall of Fame opened decades later, Duke was the only African American elected in the inaugural class. He then became the first black lineman in National Football League history in 1922, embarking on a...