Key Facts
- Campaign year
- 1341–1342
- War total duration
- 24 years
- Duke John III's death
- 30 April 1341
- Rival claimants
- Joan of Penthièvre and John of Montfort
- French king
- Philip VI (r. 1328–1350)
Strategic Narrative Overview
John of Montfort moved swiftly, garrisoning most Breton towns and castles by August 1341 and opening tentative contact with English emissaries. When Philip VI learned of these discussions, he recognised Charles of Blois as duke in September and dispatched a royal army into Brittany. Within a month John of Montfort was defeated and captured. His wife Joanna of Flanders then took command, secured the ducal treasury at Brest, stormed Redon, and held Hennebont while seeking English military support.
01 / The Origins
When Duke John III of Brittany died childless on 30 April 1341, two claimants contested the duchy: his niece Joan of Penthièvre, whose husband Charles of Blois was a nephew of French king Philip VI, and his half-brother John of Montfort. Brittany was nominally a French vassal state, and the dispute was further complicated by the ongoing Hundred Years' War between France and England, then under a temporary truce set to expire in mid-1341.
03 / The Outcome
The 1341 campaign ended with John of Montfort imprisoned and Charles of Blois installed as duke under French backing. Joanna of Flanders kept the Montfortist cause alive by enthroning her infant son as figurehead and appealing to England. The conflict was not resolved in this initial phase and continued for 24 years, repeatedly intersecting with the broader Hundred Years' War before a final settlement was reached.
Belligerents & Mobilization Analysis
Side A
1 belligerent
Philip VI of France, Charles of Blois.
Side B
1 belligerent
John of Montfort, Joanna of Flanders.
Kinetic Engagement Axis
Scroll horizontally to view full axis. Events plotted relatively.