Two rival factions, the Armagnacs and the Burgundians, vied for power within the French regency council headed by the queen, Isabeau of Bavaria.
Although two of his brothers, Antoine, Duke of Brabant, and Philip II, Count of Nevers, died fighting for France during the battle.
Finally, John and Charles agreed to seal their alliance on the bridge across the Seine at Montereau on 10 September 1419.
On 10 September 1419, the Dauphin and John the Fearless, with their men-at-arms, arrived on the two banks of the Seine, on either side of the bridge of Montereau.
John the Fearless was informed that his life was in danger, and his entourage increased its watch in order to protect the duke.
In the middle of the bridge, carpenters had put up two barriers with a door on each side, creating an enclosure for the meeting.
It had been agreed that the two rivals would enter the enclosure, each with an escort of ten people, and that the doors would be closed during the meeting.
This act would have catastrophic consequences for France, already greatly weakened by struggles for power and the French defeat at Agincourt in 1415.