Routiers
The Hundred Years' War, which lasted from 1337 to 1453, was the backdrop to their pillaging. The Hundred Years' War was fought between two royal families over control of the French throne: the Plantagenets from England, and the House of Valois from France. The War, which is divided into three stages - the Edwardian War (1337-1360), the Caroline War (1369-1389), and the Lancastrian War (1415-1429) - saw the development of new tactics and weaponry that revolutionised warfare during that time period.
War of the Breton Succession
Up to this point, the succession crisis had been a purely internal affair. But to complicate things further, the Hundred Years' War between England and France had broken out four years earlier, in 1337. In 1341, there was truce between the two countries, but there was little doubt that hostilities would be renewed when the truce ended in June 1342. Thus, when rumours reached Philip VI of France that John of Montfort had received English agents, the French Crown naturally took a more direct interest in the situation. Charles of Blois became the official French candidate. Whatever had been his original intentions, John of Montfort was now forced to support Edward III of England as King of France.