Key Facts
- Date
- Late May – late June 1342
- Conflict
- Part of the Breton Civil War (War of Breton Succession)
- Siege result
- Unsuccessful; French besiegers withdrew
- Defender
- Joanna of Montfort held the fortified port
- English relief
- Small English force arrived by sea in late June
Strategic Narrative Overview
Charles of Blois overran eastern Brittany and captured John of Montfort, after which Joanna concentrated her forces in Hennebont. When Charles arrived, an undisciplined French advance was repulsed with heavy losses and the French camp was burned. Subsequent organized assaults were also beaten back. The main French army departed, leaving a detachment to starve the town out, but a small English relief force reached Hennebont by sea in late June, prompting the blockading detachment to withdraw.
01 / The Origins
The siege arose from the Breton Civil War, a dynastic dispute between Charles of Blois and John of Montfort over the Duchy of Brittany. Philip VI of France backed Charles, his nephew, while Edward III of England had promised military aid to Joanna of Montfort, wife of the rival claimant. The ongoing Hundred Years' War between France and England complicated matters, though a truce was in effect when the siege began in late May 1342.
03 / The Outcome
The immediate siege ended with the French failing to reduce Hennebont. However, Charles was heavily reinforced in July and returned to the region, forcing the Montfortists to abandon Hennebont and fall back westward in search of larger English reinforcements. The town was saved temporarily, but the broader struggle for Brittany continued without a clear resolution at this stage.
Belligerents & Mobilization Analysis
Side A
1 belligerent
Charles of Blois.
Side B
1 belligerent
Joanna of Montfort.
Kinetic Engagement Axis
Scroll horizontally to view full axis. Events plotted relatively.