Muhammad Ali's refusal to sign his Vietnam-era military draft card upended the boxing champ's life and added a powerful voice to the anti-war movement. Now that piece of history is coming up for sale.

Muhammad Ali's refusal to sign his Vietnam-era military draft card upended the boxing champ's life and added a powerful voice to the anti-war movement. Now that piece of history is coming up for sale.

Muhammad Ali's unsigned military draft card from the Vietnam War era is being auctioned at Christie's and is expected to be sold for anywhere between $3 million-$5 million, per the Associated Press.

Add Yahoo as a preferred source to see more of our stories on Google. Muhammad Ali (left) with Rahaman in 1963, when the brothers were named Cassius and Rudolph Clay (Getty Images) A pivotal piece of ...

This image provided by Christie’s Auction House shows Muhammad Ali's draft card. (Christie’s Auction House via AP) Muhammad Ali’s refusal to sign his Vietnam-era military draft card upended the boxing ...

Muhammad Ali’s refusal to sign his Vietnam-era military draft card upended the boxing champ’s life and added a powerful voice to the anti-war movement. Now that piece of history is coming up for sale.