Douglas Fairbanks (1883-1939) holding up Charlie Chaplin (1889-1977) in front of a huge crowd to promote Liberty Bonds. Wall Street, New York.  – Wikimedia.
During World War I, Douglas Fairbanks and Charlie Chaplin teamed up with Mary Pickford (1892-1979) and toured the country at rallies to help sell Liberty bonds to help finance the war effort.
The two even decided to form their own motion picture studio together, along with Pickford and director D.W. Griffith.
The studio known as United Artists, survived in one form or another and continues to exist to this very day (although the current United Artists is pretty much just a trading name nowadays).