Alan II Barbetorte Expels the Vikings from Trans (939): The Final Phase of the Breton Reconquest

By 939, Alan II Barbetorte, Duke of Brittany, has successfully led the Breton reconquest against the Vikings who had occupied Brittany since 919. His campaign reaches a decisive moment when he drives the Norse from their stronghold at Trans, near Dol. This marks one of the final battles in the struggle to reclaim Brittany from Viking rule.

The Viking Stronghold at Trans

• Since the early 10th century, Viking forces had established fortifications in Brittany, including at Nantes, Dol, and Trans.
• Trans, near Dol, served as an important Norse stronghold, allowing the Vikings to control trade routes and launch further raids into the interior.
• Alan II, after his victories at Nantes (937) and other key locations, now turns his attention to expelling the remaining Viking forces from Brittany.

The Battle of Trans (939)

• Alan II leads a Breton force to besiege the Viking stronghold at Trans.
• After a fierce engagement, Alan’s troops overrun the Viking fort, forcing the Norse to retreat from the region.
• This breaks the last major Viking foothold in Brittany, ensuring that Breton rule is fully restored.

Consequences of the Breton Victory

1. The Final Expulsion of the Vikings from Brittany

   • With Trans recaptured, the Norse occupation of Brittany effectively ends.
   • Though occasional raids may continue, Brittany is now fully back under Breton control.

2. Alan II Becomes the Uncontested Duke of Brittany

   • His successful military campaigns make Alan II the unquestioned ruler of Brittany, strengthening the duchy’s autonomy.
   • His restoration of Breton independence ensures that Brittany will remain a distinct entity from West Francia and Normandy.

3. The Rebuilding of Brittany

   • With the Viking threat removed, Alan focuses on reconstruction, restoring churches, monasteries, and trade routes that had been devastated during the Viking occupation.

Conclusion: The Completion of the Breton Reconquest

The recapture of Trans in 939 marks the final major battle in the Breton Reconquest, ensuring that Viking rule in Brittany is permanently ended. Alan II Barbetorte, having successfully expelled the Norse, secures his legacy as the restorer of Breton independence, shaping Brittany’s future as a strong, autonomous duchy in medieval France.

The Norman Pursuit of Conan II and Harold’s Alleged Oath to William (1064–1065)

After defeating Conan II of Brittany at Dol de Bretagne, ...

The Revolt of Ralph de Gael and William’s Defeat at Dol (1075–1076)

Following the failed Revolt of the Earls (1075) in England, Ralph de Gael, Earl of East Anglia, fled to Brittany, where he seized control of Dol and sought to challenge both William I of England and Duke Hoel II of Brittany. In 1076, William led a military expedition into Brittany, laying siege to Dol, but was ultimately defeated and forced to retreat by King Philip I of France.

The Aftermath of the Revolt of the Earls (1075–1076)

• Ralph de Gael had been one of the leaders of the failed rebellion against William I in England, alongside Roger de Breteuil and Waltheof of Northumbria.
• After his defeat, Ralph fled to Brittany, while his wife defended Norwich Castle until she negotiated safe passage for herself and her followers.
• Ralph lost all his English lands and his earldom, becoming a permanent exile in Brittany, where he remained a powerful noble but no longer a player in English politics.

Ralph’s Rebellion in Brittany and the Siege of Dol (1076)

• In 1076, Ralph, rather than remaining passive, plotted against Duke Hoel II of Brittany, seizing Dol Castle and challenging the ducal authority.
• In response, Hoel laid siege to Dol, attempting to reassert control over his rebellious vassal.
• William, still interested in maintaining influence in Brittany, saw this as an opportunity to intervene militarily.
• In September 1076, William marched into Brittany and joined the siege of Dol, seeking to subdue Ralph and weaken Hoel II’s rule.

Philip I’s Intervention and William’s Defeat at Dol

• King Philip I of France, eager to check William’s expansion and maintain Capetian influence over Brittany, came to the aid of Dol.
• The French army relieved the siege, forcing William to retreat back to Normandy, marking his first significant battlefield defeat.
• Although Philip’s victory at Dol was a rare setback for William, it had little lasting impact, as William retained his control over Normandy and England.

Consequences of the Battle of Dol (1076)

• Ralph de Gael remained a Breton noble, no longer involved in English affairs.
• The battle cemented Capetian resistance to Norman expansion, as Philip I proved willing to challenge William militarily.
• William, though forced to retreat, continued to exert influence in Brittany, ensuring that his continental position remained strong.
• This was William’s first battlefield defeat, but it did not significantly weaken his power, as he remained dominant in England and Normandy.

Despite the temporary setback at Dol, William’s position in northern France remained unchallenged, and the Capetian-Norman rivalry continued, shaping the power dynamics of medieval France and England for decades to come.