Fact-based film that depicts actual events and persons. Documentaries can deal with scientific or educational topics, can be a form of journalism or social commentary, or can be a conduit for propaganda or personal expression. The term was first coined by Scottish-born filmmaker John Grierson to describe fact-based features such as Robert Flaherty's Nanook of the North (1922). Grierson's Drifters (1929) and Pare Lorentz's The Plow That Broke the Plains (1936) influenced documentary filmmaking in the 1930s. During the World War II era documentary filmmaking was a valuable propaganda tool used by all sides. Leni Riefenstahl contributed to the Nazi propaganda efforts in the 1930s; the U.S. made films such as Frank Capra's series Why We Fight (1942–45); and Britain released London Can Take It (1940). Cinéma vérité documentaries, which gained notoriety in the 1960s, emphasized a more informal and intimate relationship between camera and subject. Television became an important medium for documentary films with goals that were more journalistic (such as CBS's Harvest of Shame ) and educational (such as Ken Burns's Civil War ).