The 1940s saw Chaplin face a series of controversies, both in his work and in his personal life, which changed his fortunes and severely affected his popularity in the United States. The first of these was a new boldness in expressing his political beliefs. Deeply disturbed by the surge of militaristic nationalism in 1930s world politics, Chaplin found that he could not keep these issues out of his work. Parallels between himself and Adolf Hitler had been widely noted: the pair were born four days apart, both had risen from poverty to world prominence, and the German dictator wore the sametoothbrush moustache as the Tramp. It was this physical resemblance that supplied the plot for Chaplin's next film,The Great Dictator, which directly satirised Hitler and attacked fascism. Chaplin concluded the film with a five-minute speech in which he looked into the camera and professed his personal, anti-capitalist beliefs. Charles J. Maland has identified this overt preaching as triggering a decline in Chaplin's popularity, and writes, "Henceforth, no movie fan would ever be able to separate the dimension of politics from [his] star image".

Whether I re-entered that unhappy country or not was of little consequence to me. I would like to have told them that the sooner I was rid of that hate-beleaguered atmosphere the better, that I was fed up of America's insults and moral pomposity

I have been the object of lies and propaganda by powerful reactionary groups who, by their influence and by the aid of America's yellow press, have created an unhealthy atmosphere in which liberal-minded individuals can be singled out and persecuted. Under these conditions I find it virtually impossible to continue my motion-picture work, and I have therefore given up my residence in the United States.