The Hundred Years' War shaped medieval Europe's political landscape for over a century—but what really caused this epic conflict between England and France? In this illuminating conversation, former UK Supreme Court Justice and acclaimed medieval historian Lord Jonathan Sumption cuts through myths and misconceptions to reveal the war's true origins.

Contrary to popular belief, the war didn't begin as a simple grab for the French crown. Instead, it stemmed from a complex constitutional crisis when French kings began centralizing power over previously semi-independent territories held by English monarchs. As Lord Sumption explains, "The kings of England decided that the only way they could retain their independence as dukes of Aquitaine was to cast off the sovereignty of the French crown."

The discussion explores how England, despite being smaller and less wealthy, repeatedly triumphed on the battlefield through technological advantages like the deadly longbow and tactical innovations such as dismounted combat. We examine Parliament's crucial role in war financing and how devastating chevauchées (mounted raids) terrorized the French countryside for decades.

Perhaps most fascinating is Lord Sumption's analysis of Joan of Arc's extraordinary impact. Through "an insane degree of courage," this remarkable figure transformed French morale and fulfilled a prophecy about France's redemption by a spotless virgin. Her push for Charles VII's coronation at Reims proved pivotal in convincing French subjects of his divine right to rule.

The war's conclusion came not through a single decisive battle but through French administrative reorganization, standing armies, and Burgundy's crucial defection from the English alliance. As Lord Sumption observes, even exceptional leaders like Henry V ultimately could not overcome resource disparities—reminding us that in warfare, available resources ultimately determine outcomes.