Muhammad Ali's 1966 letter to the US Draft Board requesting religious exemption from the war in Vietnam is to auction at Heritage with a minimum bid of $50,000.
The lot is among a series of high profile pieces of sports memorabilia that will cross the block in New York on February 21-22.
It's addressed to General Lewis B Hershey and Colonel Everette S Stevenson, who served as the US directors of selective service. Ali wrote the letter following the rejection of his appeal.
Ali pens: "The issue of whether I am entitled to an appeal and also whether I am entitled to the classification of IV-D exempting me as a minister of religion should not be cast upon the waters of the judiciary to be washed back to the Selective Service System in the form of a decision when the issue in this case has already been decided by the courts in my favor and both I and the Selective Service System would be put to unnecessary expenses and hardships in order to get my rights protected in the judiciary..."
His refusal to fight meant he was stripped of his world heavyweight title and banned from boxing for four years.
He became a potent symbol of America's countercultural revolution.
Heritage describes this letter as "the most significant Ali document in existence".
The sale will also include the gloves worn by both Ali and Sonny Liston in the legendary 1965 "phantom punch" bout.
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