The Treaty of Amiens, signed on 13 April 1423, was a defensive agreement between Burgundy, Brittany, and England during the Hundred Years' War.

By the agreement, all three parties acknowledged Henry VI of England as King of France, and agreed to aid each other against the Valois claimant, Charles VII.

The accession of an infant king made it easier for the French nobility to refuse him and support the Valois heir, Charles.

The main part of the agreement was the signatories commitment to work for "the good of our lord the king and his kingdom of France and England", a clause that recognised Henry VI's title to the French throne, and rejected the authority of Charles.

On 18 April 1423, the Bretons and the Burgundians held a secret meeting in which the two agreed to remain friends if either duke would reconcile himself with Charles.

By 1433, the Duke of Burgundy opened negotiations with Charles, and, having only agreed with a small peace settlement near Burgundian-Valois territory, he now started reflecting on a possibility of a Franco-Burgundian reconciliation.

Burgundy had a Papal legate which enabled him to break the oath he had made at Troyes, and reconciled with and recognised Charles as King of France.

When it declared war on England in 1426, Brittany's eastern frontier remained unprotected, besides sending raids into English held territory.