
Why We Fight is a series of seven documentary films produced by the US Department of War from 1942 to 1945, during World War II. It was originally written for American soldiers to help them understand why the United States was involved in the war, but US President Franklin Roosevelt ordered distribution for public viewing.

The Battle of Britain was the fourth of Frank Capra's Why We Fight series of seven propaganda films, which made the case for fighting and winning the Second World War. It was released in 1943 and concentrated on the German bombardment of the United Kingdom in anticipation of Operation Sea Lion, the planned German invasion.

The Battle of China (1944) was the sixth film of Frank Capra's Why We Fight propaganda film series.

The Battle of Russia (1943) is the fifth film of Frank Capra's Why We Fight documentary series. The longest film of the series, it has two parts. It was made in collaboration with Lithuania-born Anatole Litvak as primary director under Capra's supervision. Litvak gave the film its "shape and orientation," and the film had seven writers with voice narration by Walter Huston. The score was done by the Russian-born Hollywood composer Dimitri Tiomkin and drew heavily on Tchaikovsky along with traditional Russian folk songs and ballads.

Divide and Conquer (1943) is the third film of Frank Capra's Why We Fight propaganda film series and deals with the Nazi conquest of Western Europe in 1940.

The Nazis Strike is the second film of Frank Capra's Why We Fight propaganda film series. It introduces Germany as a nation whose aggressive ambitions began in 1863 with Otto von Bismarck and the Nazis as its latest incarnation.

Prelude to War is the first film of Frank Capra's Why We Fight film series commissioned by the Office of War Information (OWI) and George C. Marshall. It was made to educate American troops of the necessity of combating the Axis powers during World War II based on the idea that those in the service would fight more willingly and ably if they knew the background and the reason for their participation in the war. The film was later released to the general American public as a rallying cry for support of the war.

War Comes to America is the seventh and final film of Frank Capra's Why We Fight World War II propaganda film series.