The Battle of Agincourt, fought on 25 October 1415, has gone down in history as one of the most iconic events in the story of England. Yet, dramatic though it was, it was only the beginning of a long and gruelling campaign that brought Henry V to the verge of greatness. The second invasion of France post-Agincourt often receives little more than a sideways glance, yet it is a fascinating example of a medieval military campaign. Characterised by sieges and diplomatic and political manoeuvring, not to mention bloodshed and murder, the campaign of 1417–22 also introduces a host of fascinating characters including the scheming John the Fearless, duke of Burgundy, a mentally unstable French king and his politically astute wife, and their disinherited son and heir. Yet it is Henry V who dominates the scene. The campaign showed Henry to be not just an outstanding warrior – which he undoubtedly was – but a man driven by burning ambition who would not tolerate opposition. The ruthless king would have been difficult to love but easy to respect, and the events of his post-Agincourt campaign demonstrate this magnificently. Henry came within an ace of becoming king of both England and France. He was only deprived of the distinction by his premature death just two months before Charles VI of France died. What might have happened had Henry lived longer is one of the great what-ifs of history. Yet even this cannot diminish his greatness.