In 1372, John of Gaunt began claiming the Castilian throne due to his marriage to a daughter of the reigning king, and by 1373, he had a plan to invade the country and depose the incumbent Henry II. In 1374, he made a pact with Charles the Bad of Navarre to allow his armies passage through the country. However, only a few days after this agreement was reached, he returned to England and abandoned the plan. How would the history of Europe be different if this plan had succeeded?