The project, adapted from James McBride's book The Miracle at St Anna, follows the 92nd 'Buffalo Soldiers' division, which became stranded behind enemy lines in Tuscany and encountered a harrowing Nazi massacre in a local village.
Lee insists the soldiers' contribution to the war has largely been ignored, while posthumous medals of honour weren't awarded until the late 1990s.
He says, "If you look at the history of Hollywood movies, the negro soldiers who fought in World War II are invisible."
Source: WENN