How Diplomacy Helped the English win the Battle of Agincourt

One of the most important victories for the English in the Hundred Years War took place at Agincourt on October 25, 1415. It marked a key turning point in the long-running conflict between England and France. In a paper given earlier this month, Christopher Given-Wilson argues that it was the diplomatic maneuverings of Henry IV in the years 1407 to 1413 that set the stage for his son to win the battle.

Lambeth Palace Library Ms 6 f.243 - Battle of Agincourt

He believes that part of the reason why the English suffered setbacks between the 1370s and the early 1400s was that on the diplomatic front they were involved in numerous conflicts, including wars in Iberia and the Low Countries, as well as the outbreak of a Papal Schism. These situations not only used up English resources but also prevented them from focusing on their main rival. Given-Wilson, a professor at the University of St Andrews, spoke at the International Congress on Medieval Studies on the topic of ‘The Duke of Clarence’s Expedition to Guyenne in 1412–13’. He began his paper by noting that most historians view the Hundred Years War as having four phases - English success in the early years of the conflict, then reversals in the late fourteenth and early fifteenth centuries, followed by new successes starting in 1414, and finally failure as they were driven out of most of France over the period 1428 to 1453.

When Henry IV obtained the English throne in 1399, he stated many times that he wanted to sail to France to press his claim to that kingdom as well. However, he never did go abroad during his reign, but in the words of Given-Wilson spent his time “clearing the diplomatic undergrowth.” Between 1407 and 1412 he was able to accomplish a number of international successes - normalized trade relations with the Hanseatic League, truces with Brittany and the Low Countries, and improving relations with Castile and other Iberian kingdoms. Moreover, by 1409 he was able to suppress the Welsh Revolt of Owain Glyndŵr, and the fortunate capture of James I of Scotland in 1406 helped to create a long term truce with the Scots.

The diplomatic successes of the English was followed by the Duke of Clarence’s military expedition to France in the years 1412-13. Given-Wilson explained that this campaign “has been consistently downplayed and consistently misunderstood,” as it capitalized on infighting among the French to make important gains. With just a force of 4000 men, the Duke, who was King Henry’s second eldest son Thomas of Lancaster, was able to force the French king to pay him £40,000 to have him go away to Bordeaux. Once there, he was able to retake large parts of the region of Gascony.

The campaign would secure English possessions in southern France, allowing them to concentrate future fighting in the northern part of the country, and leave the court factions in France more divided than ever. Along with the diplomatic work done by Henry IV, which would keep England away from other conflicts and distractions, this success would form the prelude for Henry V’s campaign in 1415, one that would lead to the fields of Agincourt.

You can read more about the Battle of Agincourt in this special issue of Medieval Warfare magazine.

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