 On March 31, 1921, a few sources have Brennan losing to talented Black boxer Jeff Clark in Atlantic City, New Jersey.Clark would fight some of the greatest Black boxers of his era including Kid Norfolk, Sam McVea, Harry Wills, and Sam Langford.Clark had taken the Panamanian Heavyweight Title in Panama City, Panama, defeating Kid Norfolk on May 16, 1915, and had taken the Mexican Heavyweight title earlier.