Sobolewski (who was also known in Canada as Sigmund Sherwood or Sigmund Sherwood-Sobolewski) traveled the world following the war and settled in Canada in 1949. In 1967, he was engaged as an activist opposed to neo-Nazism. While living in Toronto, he was among the demonstrators at an event attended by 6,000 people at the Toronto Coliseum to "denounce the rise of neo-Nazi forces in Germany." He went on a 7,000-mile trip across Europe to demand that West Germany compensate members of his Former Prisoners Association, all of whom had been in Nazi camps. He also initiated his activity protesting against neo-Nazism by donning a facsimile of his Auschwitz prison uniform and picketing the appearance of a German neo-Nazi leader on Canadian television.