War of the Breton Succession
The French–Breton War (Breton: "Brezel etre Breizh ha Bro-C'hall", "War between Brittany and France"; French: "Guerre de Bretagne", "War of Brittany") lasted from 1487 to 1491. The cause of this war was the approaching death of the Breton Duke Francis II of Brittany (died 9 September 1488), who had no clear successor. If not resolved, this meant a resumption of issues from a previous War of the Breton Succession (1341–1364), which had rival claimants allying with England or France, resulting in an ambiguous peace treaty that failed to prevent future succession disputes.