When Henry V, victor of Agincourt, died in August 1422, future history was changed catastrophically. Had he lived another couple of months he would have been king of France. His premature death left his son, the infant Henry VI, on the English throne. He would turn out to be pious, weak and prone to bouts of insanity, and provided the catalyst for the Wars of the Roses.

With the reigning Lancastrian house in disarray, it was inevitable there would be a challenge and it came from the rival royal house of York. Its head was lopped off in December 1460 when Richard, Duke of York, was decapitated after falling in the Battle of Wakefield, but like the hydra it grew another in the form of Edward, Earl of March, the 18-year-old, 6 foot 4 leviathan, and future Edward IV.