Conversation so far:
what is the famous photo in question?
A photo of a dazed Tittle in the end zone taken by Morris Berman of the Pittsburgh Post-Gazette on September 20, 1964.
what is special about it?
Tittle, in his 17th and final season, was photographed helmet-less, bloodied and kneeling immediately after having been knocked to the ground.
who was he knocked by?
John Baker of the Pittsburgh Steelers.
why was he bloodied?
He suffered a concussion and cracked sternum on the play, but went on to play the rest of the season.
was the photo published in all the papers?
Post-Gazette editors declined to publish the photo, looking for "action shots" instead.

Question: so how did it become famous?
Self-contained rewrite: so how did photo of dazed Tittle become famous?