It gained prominence as a leading organizer of opposition within Canada to Nazi Germany following Hitler's rise to power and as an opponent of fascist groups organizing within Canada in the years leading up to World War II.
[1] The organization attempted to build support across a cross-section of people outside of the Communist Party and attracted affiliations by some trade union locals about a dozen Co-operative Commonwealth Federation clubs and several youth groups.
[8] The League was active in denouncing fascist groups in Canada such as the Canadian Nationalist Party, the Canadian Union of Fascists, and the National Unity Party of Canada, opposed Quebec's Padlock Law, protested the persecution of Jews in Europe,[9] and called for a boycott of Japanese goods after Japan's attack on China in 1937, and warning Canadians about Nazi Germany and fascist Italy.
[3] MacLeod resigned as chairman on August 23, 1939,[14] the day the announcement was made of the Molotov–Ribbentrop Pact, the non-aggression treaty between Josef Stalin's Soviet Union and Adolf Hitler's Nazi Germany which ended the Communist Party's anti-fascist activity until Nazi Germany invaded the Soviet Union in 1941.
The league was banned in 1940, along with the Communist Party itself and other allied organizations, under the Defence of Canada Regulations.