For what courageous expression of opinion did Alexander Altmann, the communal Rabbi in Manchester, become known in the fifties?

His support was instrumental in Bert Trautmann - a former Nazi sergeant and British prisoner of war - being accepted into the squad of Manchester City as a goalkeeper.

This was in spite of him being Jewish (and a fugitive from Nazi Germany) as well as in spite of the substantial Jewish fan following of the club at the time - so Trautmann was certainly not the most obvious prospect for him to endorse.

Trautmann's spell at the club was initially met by resistance from the fans, but he quickly became a mainstay of the team and was among those responsible for the club's good results in the 1950s.

(It should be noted that Trautmann, while a member of the Wehrmacht and Nazi party, was not directly involved in any crimes against Jews. Still, this was a tall order for someone who had to flee his home country due to persecution.)

https://en.wikipedia.org/wiki/Bert_Trautmann
https://en.wikipedia.org/wiki/Alexander_Altmann