The Treaty of Arras in 1435 was a significant diplomatic agreement that altered the course of the Hundred Years' War between England and France. Before this treaty, the Duchy of Burgundy had been a crucial ally of England, enabling the English forces to maintain a strong presence in Northern France. The negotiations that led to the treaty were arduous, as they required addressing grievances on both sides. Duke Philip the Good, initially allied with England, was persuaded to reconsider this alliance due to various factors, including the ambitious reign of Charles VII and the desire for peace within his territory, which had been troubled by ongoing hostilities.

The Treaty was not solely about changing allegiances; it involved the recognition of Philip's claims and interests within the French kingdom. As a result, this treaty promised territorial concessions and financial arrangements that were favorable to Burgundy, enhancing the economic stability of the region. The shift in allegiance was pivotal, as it not only reinforced France's military position but also showcased the strategic importance of Burgundy in the broader context of the war.

In the aftermath, the treaty contributed to a series of French victories against the English, leading to a gradual decline of English influence in France. This new alliance emboldened French forces, particularly influencing subsequent battles and campaigns in the latter part of the Hundred Years' War, ultimately shaping the geopolitical landscape of France for generations. The Treaty of Arras stands as a testament to the significance of diplomacy and political maneuvering in medieval warfare, demonstrating how alliances could pivot dramatically under the right circumstances.