The Breton Civil War was a dynastic dispute between two claimants to the Duchy of Brittany which broke out in May 1341, after the death of Duke John III. A complicating factor was the ongoing Hundred Years' War between France and England. Philip VI of France supported the claim to the duchy of his nephew, Charles of Blois; Edward III of England backed the rival claimant, John of Montfort. John seized most of the fortified places in Brittany in 1341, but a French army sent to support Charles overran eastern Brittany and captured John in November. John's wife, Joanna of Montfort, took command of her husband's field army, set up her two-year-old son, also named John, as the faction's figurehead and heir to his father's claim to the duchy, and appealed for English military intervention. A truce between France and England was in place, but it was due to expire in June 1342.
In late May 1342 Charles led an army against the small but strongly walled port of Hennebont where Joanna was based. Repeated assaults were rebuffed, but the delayed arrival of English reinforcementscaused by lack of shipping and bad weatherforced the Montfortists to retreat to the extreme west of Brittany. The English arrived in August, relieved Brestwhere Charles was again besieging Joannaand inflicted a heavy defeat on Charles at the battle of Morlaix, the first land battle of the Hundred Years' War. Edward III arrived with further English reinforcements, besieged Vannes, and in turn overran most of Brittany. Attempts to reinforce or supply Edward from England failed and a French army greatly outnumbering the Anglo-Montfortist force was raised and advanced to Malestroit, from the English camp. Philip entered into negotiations with Edward and the Truce of Malestroit, which was supposed to pause hostilities for three-and-a-half years, was agreed on 19 January 1343.
A peace conference was arranged in Avignon where, mediated by Pope Clement VI, a treaty to permanently end the war was to be drafted. The conference did not convene until late 1344, due to English quibbling over the arrangements. The proposals made by each side were unacceptable to the other. Neither displayed any willingness to compromise, and the conference rapidly collapsed. After mutual provocations Edward formally renounced the truce on 15 June 1345 and full-scale war resumed. Despite the truce, the Breton Civil War had been grinding on as a disjointed and inconclusive series of petty sieges and skirmishes. The English and their Montfortist allies held almost the whole of Brittany by 1345. The Breton Civil War continued until 1365, the Hundred Years' War until 1453.
Background
Since the Norman Conquest of 1066, English monarchs had held titles and lands within France, the possession of which made them vassals of the kings of France. By the first quarter of the fourteenth century, the only sizeable French possession still held by the English in France was Gascony in the south west. Following a series of disagreements between Philip VI of France and Edward III of England, on 24 May 1337 Philip's Great Council agreed that the lands held by EdwardIII in France should be taken back into Philip's hands on the grounds that Edward was in breach of his obligations as a vassal. This marked the start of the Hundred Years' War, which was to last 116 years.
On 26 January 1340 Edward formally claimed the French throne. The immediate effect was to allow the Flemings to join his cause without technically disowning their fealty to the French crown and therefore becoming rebels. The extent to which Edward considered the claim more than a negotiating position is unclear. In June the French navy was annihilated by the English fleet at the battle of Sluys and in July Edward invaded north-east France at the head of a large, heavily subsidised, allied army. The allies laid siege to Tournai on 1 August. On 7 September the French army arrived, but Philip held it back to ensure there was no risk of a battle occurring. He was probably aware that the allied army was falling apart, with the English unable to pay their allies what they had been promised, or even to feed them. Negotiations for a pause in the fighting were opened, mediated by emissaries of Pope Benedict XII. The Truce of Espléchin was rapidly agreed, to last from 25 September 1340 to 24 June 1341. The allied armies left France thereafter. The English Crown, bankrupt, was unable to meet its commitments, and Edward fled the continent to avoid his creditors.
Civil war in Brittany
Brittany was a province of France, but although the dukes of Brittany were vassals of the French kings they governed the duchy as independent rulers. Nevertheless, when the Hundred Years' War broke out in 1337 between France and England the duke of Brittany, John III (), fought alongside his feudal lord the king of France. John III died on 30 April 1341, leaving a disputed succession, with both his niece, Joan of Penthièvre, and his younger half-brother, John of Montfort, claiming the duchy. Joan's claim was exercised through her husband, Charles of Blois, a well-connected and militarily oriented French nobleman who was also a nephew of King Philip of France.
On John III's death John of Montfort acted quickly and installed friendly garrisons in most of the towns and castles of Brittany by August. The Parlement of Paris was the supreme judicial authority in France and on 7 September, at Philip's urging, it declared that Charles of Blois was the legitimate successor to John III. Philip found the idea of having a relative as the duke attractive because it would bring the traditionally semi-autonomous province more firmly under royal control. He was willing to commit considerable military resources to achieve this and despatched an army, commanded by his eldest son, John, Duke of Normandy, to support Charles.
This army overran all of eastern Brittany except Rennes and took John of Montfort prisoner. John's wife, Joanna of Montfort, was in Rennes when news of John's capture arrived. She acted decisively, recalled the field army from western Brittany, took command and moved to Hennebont, a small but strongly walled town with access to the sea. From there Joanna retained control of most of western Brittany and set up her two-year-old son, also named John, as the faction's figurehead and heir to his father's claim to the duchy. She despatched her senior counsellor, Amaury of Clisson, to Edward III, the English king, with the ducal treasury to encourage English military intervention and waited on events.
On 21 February 1342 Edward sealed a treaty to support the Montfort cause as an extension of the war with France. Edward saw the opportunity to set up a ruler in Brittany at least partly under his control; this could provide access to Breton ports which would greatly aid England's naval war and give ready entry to France for English armies. In May 1342 Clement VI became pope. He was strongly pro-French and had previously been one of Philip's senior advisers. He despatched two cardinals to attempt to broker a permanent settlement of the Anglo-French war. The following month they were well received by Philip in Paris; Edward, on the other hand, would not even allow them to cross the Channel.
English intervention
English reinforcements took a long time to arrive and in May 1342 Rennes fell, allowing Charles to march on Hennebont, part of a general offensive to push his area of control westward. On arrival at Hennebont several units of Charles's army advanced against orders and attacked some of the town's defenders who were formed up outside its gate. More troops were pulled into this fight before the French were pushed back in a disorderly retreat. The Montfortists pursued, inflicting many casualties and burning the French camp. According to a contemporary account Joanna rode through the suburbs in full armour encouraging the fighting men. Two days later the French launched a series of better-planned assaults on the town's walls, but all were repulsed with losses. The main French force moved on, leaving a detachment to carry out a regular siege in an attempt to starve the town into surrender.
A fleet of French and mercenary galleys cruised off the north Breton coast, but there was so little English naval activity that they were beached and their crews went ashore to fight as infantry. Edward planned to land in Brittany himself in June with a substantial force, but extreme difficulty in assembling ships, despite draconian measures taken by Admiral Robert Morley, and then contrary winds, caused this date to be repeatedly put back.
While waiting for English reinforcements the flow of events went against the Montfortists in the face of Charles's huge military superiority. Having taken Vannes, he moved on to besiege Auray and, again, Hennebont; both fell. By August little was left of Joanna's forces, most of whom were besieged in the western port of Brest by a large army and blockaded from the sea by 14 mercenary Genoese galleys. Brest was on the brink of surrender when the English arrived on 18 August. Their fleet of 140 converted merchantmen and an unknown number of galleys took the Genoese galleys by surprise and 11 were burnt.
The English ships carried 1,350 men, a force far inferior to that of the French besieging Brest. But, seeing so many English ships crowded into the Brest Roads and the English vanguard disembarking onto the beach, they anticipated an attack by a vast host. Charles promptly broke off the siege and withdrew , abandoning western Brittany, where the populace strongly favoured the Montfort cause. Part of Charles' force withdrew along the south coast of Brittany, but the bulk of the army accompanied him to Guingamp. Here he concentrated his forces and called up local levies. The English were commanded by William, Earl of Northampton, who was reinforced by 800 men under Robert of Artois a few days after landing. He also absorbed several other small English forces and an unknown number of John of Montfort's Breton partisans. Northampton's first mission was to secure a port for the main English army to disembark at.
English offensives
The English marched from Brest to Morlaix, a port on the north coast of Brittany with strong fortifications and a secure harbour, and laid siege to it. Edward's contingent was still in England waiting for the ships which had transported Northampton's echelon to return. The French mistakenly believed this army would be used in north-east France, probably disembarking in Picardy. A French army was gathered to confront this imagined threat, including many men transferred from Brittany. Charles became aware his force greatly outnumbered the English, despite the detachments to Picardy, and took his army west in an attempt to relieve Morlaix.
Warned of this, the English carried out a night march and prepared a defensive position on the Guingamp-Morlaix road. When they sighted the English position, the French deployed into three divisions, one behind the other. The first of these, probably made up of Breton levies, advanced and was shot to pieces by the English archers using longbows; it then broke without making contact. The second division, of French and Breton men-at-arms, attacked but their charge was halted when they fell into a camouflaged ditch in front of the English position. Presented with a large, close-range target the English archers inflicted many casualties. About 200 French cavalry made their way over the ditch and came to grips with the English men-at-arms, who were fighting on foot. This band was cut off by the English and all were killed or captured.