Portugal struggles for its very existence against the mighty Castile (Spain) invasion drawing in Britain and France during the Hundred Year's War in Medieval Europe.

An epic medieval documentary movie set during the Hundred Year's War involving Britain, France, Castile (Spain) and Portugal. Focusing on the Portuguese battles against the Castilian invasion that led to one of the mightiest victories and humiliating defeats in military history. Britain's House of Lancaster formed an alliance with Portugal's House of Aviz that became the longest-running alliance between the two nations that stands to this day.