The Hostage Collateral

The Treaty of Brétigny and How Mortal Enemies Trade Without Trust

Unrolled across the oak tables of the village of Brétigny near Chartres in May 1360, the thirty-nine Latin and Anglo-Norman articles of peace between King Edward III of England and King John II of France read less like a treaty of reconciliation than a high-stakes pawnbroker's ledger of human flesh. For twenty-three years, the opening phase of the Hundred Years' War had devastated the French countryside through English chevauchées—scorched-earth cavalry raids designed to burn crops, loot towns, and humiliate the Valois crown. Four years earlier, on September 19, 1356, at the Battle of Poitiers, Edward the Black Prince had routed the French royal host and captured King John II (John the Good) himself along with his fourteen-year-old youngest son Philip on the battlefield.

Held in gilded captivity in England at Savoy Palace and Windsor Castle, King John faced the central dilemma of every blood rivalry that attempts to negotiate an exit: how can two adversaries conclude a sequential transaction when mutual trust is zero and no supranational court exists to enforce the contract? Edward III agreed at Brétigny to renounce his claim to the throne of France and release King John so the French monarch could return to Paris and raise a ransom of three million gold crowns (écus d'or—roughly £500,000, more than twice the annual revenue of the English crown) alongside the transfer of sovereign territory across Aquitaine, Poitou, and Calais. Yet the moment Edward III allowed John II to sail across the English Channel to collect the first installment of gold, what stopped the French king from repudiating the parchment inside the walls of Paris?

Six centuries before the Nobel laureate economist Thomas Schelling formalized the theory of credible commitments and hostage exchange in The Strategy of Conflict (1960), medieval English and French diplomats solved the enforcement gap by replacing verbal promises with an intricate, self-executing architecture of asymmetric physical collateral:

• The Royal Blood Tranche (Hostages of the Lily)*: Before King John II was permitted to step off the gangplank as a free sovereign at Calais in October 1360, France was required to hand over forty top-tier nobles into English custody, headed by the immediate royal bloodline: the king's second and third sons, Louis, Duke of Anjou, and John, Duke of Berry; the king's brother Philip, Duke of Orléans; and the king's cousin Louis II, Duke of Bourbon, alongside counts and marshals captured at Poitiers.
• * The Municipal Burgher Tranche: Because aristocratic pride alone did not control the urban tax vaults needed to coin three million gold crowns, the Treaty of Brétigny required the delivery of forty bourgeois hostages—two of the wealthiest merchants and magistrates from each of twenty major French cities, including four from Paris and two each from Rouen, Lyon, Reims, Toulouse, Orléans, and Amiens.
• * The Rotational Parole and Default Clause: Held in honorable custody in London and Calais, the hostages were permitted to hunt, hawk, and dine at court at their own considerable expense, while a strict release schedule stipulated that one-fifth of the hostages would be freed each time a 600,000-crown installment and a corresponding territorial transfer cleared the English Exchequer. If France defaulted on the schedule, all released territory reverted and the hostages remained permanent forfeits.
• * The Four Dukes of the Lily Agreement (November 1362): When plague and tax revolts slowed the collection of French gold and only 400,000 crowns had arrived after two years, the four royal princes grew desperate to leave England. They negotiated a supplemental sub-treaty transferring themselves to the English enclave of Calais on four-day paroles so they could personally pressure the French estates to deliver the remaining castles and bullion.

Schelling pointed out that a hostage mechanism works only when the party posting the bond values the collateral's honor and return more highly than the profit of defection. In autumn 1363, young Louis, Duke of Anjou, used his four-day parole from Calais to make a pilgrimage to Our Lady of Boulogne, met his young wife Marie of Blois at the Castle of Guînes, and refused to return to English custody. When his father King John II learned that his own son and heir-substitute had broken the sacred chivalric oath that guaranteed the crown's credit, he declared to his council that if good faith were banished from the rest of the world, it must still be found in the mouths of kings. Despite the pleas of his ministers, King John II voluntarily sailed back across the English Channel in January 1364 and surrendered himself into English captivity in London, where he died at the Savoy Palace four months later.