On 13th April a tripartite agreement had been formalised between England, Burgundy, and Brittany. The Treaty of Amiens was a defensive treaty in which each of the states agreed to aid each other in the event of an attack by the French, and to support King Henry VIs right to the French crown over that of Charles of Valois. To strengthen these links against France, the Duke of Bedford, and the Breton Arthur de Richemont would marry sisters of the Duke of Burgundy.
Treaty of Troyes
The Treaty of Troyes had promised inheritance of the French crown to King Henry V of England, or his heirs, at such time as the French King, Charles VI. Charles had died shortly after the treaty was signed. So too, had Henry V of England. This left Henry VI of England, an infant, as the King of England and as the heir to the French throne. At the same time, Charles VI of France’s son lay claim to the throne which had, by Treaty, been passed to the English upon his father’s death.
Treaty of Amiens
The Treaty of Amiens was intended to make certain of the alliance between England, Burgundy and Brittany in these uncertain times. With the leadership of both England and France having changed, and there being a threat to the agreed inheritance in France, a resurgence of war seemed quite probable. At Amiens, the agreement was that war with one, meant war with all.
For the continental Duchy’s of Burgundy and Brittany, the situation was quite complex. Though allied to England, they were Duchy’s of France. Whilst acting largely independently of the French crown, they remained subjects. Now the crown was in the hands of Henry VI of England, but this could quite easily change.
Burgundy and Brittany’s concerns
Burgundy and Brittany border French lands. They were susceptible to any attack from the Valois claimant, Charles VII. Whilst England could aid either of the Duchy’s, the two Dukes would be hard pressed to send aid to the other quickly. Geography alone made it difficult.
Secret Treaty between Burgundy and Brittany, 18th April 1423
Recognising that either side may be put into a position it was most sensible to agree terms with the Valois claimant, Charles VII, the Burgundians, and Bretons agreed a secret addition to the Treaty of Amiens. Should either come to terms with Charles VII, the two Duchy’s would remain on friendly terms and not aid Charles VII against the other.