The Treaty of Guérande: March 14, 1369

The Treaty of Guérande, signed on March 14, 1369, marked the official end to the protracted conflict known as the War of the Breton Succession. This war, which spanned from 1341 to 1364, was essentially a dynastic dispute over the Duchy of Brittany, involving competing claims following the death of Duke John III, who left no direct heir.

Key Context Leading to the Treaty

• War of the Breton Succession: The conflict arose between two main factions:

  • John de Montfort: Representing the House of Montfort, backed by England.
  • Charles of Blois: Representing the House of Blois, supported by France.

• The war was deeply intertwined with the larger scope of the Hundred Years’ War between England and France, as both claimants aligned themselves with the respective opposing crowns.

• Battle of Auray (1364): A decisive battle where John de Montfort, with English support, defeated the troops of Charles of Blois, leading to Charles’ death and paving the way for John IV (son of John de Montfort) to press his claim.

Details of the Treaty

• Recognition of John IV: The Treaty of Guérande recognized John IV as the Duke of Brittany, officially confirming his lordship over the region.

• Allegiance to France: While acknowledged as duke, John IV was expected to render homage to Charles V, the King of France, cementing an agreement to act as a vassal which inherently assured Brittany’s status as a semi-independent appanage under French sovereignty.

• Restoration of Stability: The treaty effectively ended the civil war within Brittany, providing much-needed peace and stability after over two decades of turmoil, and allowed for economic recovery and consolidation of power by the new ducal authority.

Aftermath and Significance

• Brittany’s Position: While Brittany retained considerable autonomy, John IV’s allegiance to France mitigated future disputes between England and France over the region, at least temporarily.

• Long-term Impacts: The Treaty of Guérande represented an instance of medieval conflict resolution through diplomacy and legal agreements, setting a precedent for future negotiations in the region. It also reflected the complex feudal relationships of the time and the impact of the Hundred Years’ War on regional politics.

By establishing John IV officially as Duke, the treaty helped maintain a delicate balance of power in Western Europe and illustrated the ongoing shifts of alliances typical of the era.