War of the Breton Succession
The Battle of Champtoceaux, often called the Battle of l'Humeau, was the opening action of the 23-year-long War of the Breton Succession, a dynastic conflict in Brittany which became inevitably embroiled in the Hundred Years War between England and France. This battle should have decided the war at a stroke, as John of Montfort, the leader of one faction, was made prisoner. However his wife, Joanna of Flanders, and young son John escaped imprisonment. Their escape and continued support from his ally, England, allowed continued resistance to flourish and eventually turn the tide.