Saintonge War
In English history, the ‘Hundred Years’ War’ refers to the 116-year period between 1337 – 1453. In some French accounts, that period of conflict is referred to as the ‘Second Hundred Years’ War’, the first embracing the period of upheaval following the change in the balance of power between the French and English thrones from 1159 to 1259 after Henry II of England married Eleanor of Aquitaine gaining many French territories in the process and achieving territorial superiority over the French Kingdom, until the Treaty of Paris (1259), in which the opposite became true. This period saw many conflicts and battles between the two kingdoms such as the Anglo-French War (1202–1214) or the Battle of Bouvines.
Brittany
The Breton War of Succession, a local episode of the Hundred Years' War, saw the House of Blois, backed by the French, fighting with the House of Montfort, backed by the English. The Montforts won in 1364 and enjoyed a period of total independence until the end of the Hundred Years' War, because France was weakened and stopped sending royal envoys to the Court of Brittany. English diplomatic failures led to the Breton cavalry commanders Arthur, Comte de Richemont (later to become Arthur III, Duke of Brittany) and his nephew Peter II, Duke of Brittany playing key roles on the French side during the deciding stages of the War (the Battle of Patay, the Treaty of Arras (1435), the Battle of Formigny and the Battle of Castillon). However, Brittany lost the Mad War against France in 1488, mostly because of its internal divisions which were exacerbated by the corruption at the court of Francis II, Duke of Brittany. Indeed, some Breton lords were fighting on the French side.