According to article on Vulture, yes.
Wikipedia states,
The film was directed by Chaplin (with his half-brother Wheeler Dryden
as assistant director), and written and produced by Chaplin. The film
was shot largely at the Charlie Chaplin Studios and other locations
around Los Angeles.
From Vulture,
The Great Dictator has rightly been held up as an example of Hollywood
not caving to the wishes of foreign tyrants
Plus, Chaplin had already run afoul of the Nazis, who thought
(erroneously) that he was Jewish, banned his films, and even called
him “a disgusting Jewish acrobat” in one of their publications. When
he visited Berlin in 1931 to promote City Lights — well before
Hitler’s rise to the chancellorship in 1933 — pro-Nazi media had
effectively run him out of town, calling him an “anti-German
warmonger” and an “American film-Jew.” Footage of Chaplin’s visit
would be used in the notorious Nazi propaganda film, The Eternal Jew.
(“It cannot be denied that one part of the German people
enthusiastically applaud the foreign Jews who come to Germany — the
deadly foes of their race,” the film’s narrator breathlessly warned,
over shots of adoring crowds greeting Chaplin.)
The reason for him to do this alone because studios had doubts in the war. as stated in Vulture,
But in 1938, when Chaplin announced that he was setting forth to make
The Great Dictator, Hollywood was extremely wary of picking sides in
the approaching war. Studios deliberately shied away from commenting
on events in Europe and made it a point to take out any material that
could be construed as overtly supporting U.S. intervention. Part of it
was due to financial relationships they had with the German film
market. Part of it was a fear of very vocal isolationists in the U.S.
Studio heads also worried that they would themselves become the
targets of anti-Semitic attacks if they pressed too hard for war.
In his book, Five Came Back: A Story of Hollywood and the Second World War, Mark Harris describes the tension in Hollywood thus:
Even as most studios maintained a strong financial interest in the
German market and continued to do business with Hitler and his
deputies, the issue of how to fight Hitler’s rise to power was
becoming a subject of discussion, and discomfort, in their boardrooms
and executive suites. But in 1938, all of Hollywood’s major
moviemaking companies … were adamant on one point: Whatever they
thought about the Nazis, they would not allow their feelings, or
anyone else’s, about what was happening in Germany to play out
onscreen. On rare occasions, a veiled or allusive argument against
Fascism or tyranny would make its way into a motion picture, but it
was then unthinkable that studios could use their own movies to sway
public opinion about Hitler without sparking instant accusations that
they were acting as propagandists for foreign – meaning Jewish –
interests. Much of Hollywood’s creative class – directors, writers,
actors, independent producers – was becoming far more forthright about
making its political sympathies known at rallies and in aid
organizations, but for the most part, the noise they were making
stopped when they passed through the gates and reported for work every
morning.
Chaplin, however, had his own studio and could afford to self-finance much of his film. That’s not to say that he wasn’t met with enormous resistance when he initially announced it in 1938. United Artists, the studio he had co-founded, was nervous and worried that the film could not be shown in England, for fear of offending the Germans. Chaplin was fearless.
He himself tells about the problems he had to face in his autobiography:
Half-way through making The Great Dictator I began receiving alarming
messages from United Artists. They had been advised by the Hays Office
that I would run into censorship trouble. Also the English office was
very concerned about an anti-Hitler picture and doubted whether it
could be shown in Britain. But I was determined to go ahead, for
Hitler must be laughed at…More worrying letters came from the New York
office imploring me not to make the film, declaring it would never be
shown in England or America. But I was determined to make it, even if
I had to hire halls myself to show it…Before I had finished The
Dictator England declared war on the Nazis… Then suddenly the
holocaust began: the break-through in Belgium, the collapse of the
Maginot Line, the stark and ghastly fact of Dunkirk -- and France was
occupied. The news was growing gloomier. England was fighting with her
back to the wall. Now our New York office was wiring frantically;
“Hurry up with your film, everyone is waiting for it.”
There were certain fears at the studios, that made him do all the work himself, which also indicates sometimes he had to face more than just concerns about germany from the studios.
