This documentary summarizes the situation of the 100 Years War between England and France.  It was caused by King Phillip VI of France claiming to be the legitimate ruler of France and Britain in 1328 due to being the first cousin of Charles IV who had no sons, while King Edward III of England also claimed to be the rightful heir due to being the son of Isabella of France, who was the daughter of Charles IV.  The war ended with England and France having clearly defined national identities, followed by the “War of the Roses” soon being fought to determine who would control the throne of England.