King John’s Rebellion: The First Barons’ War

Magna Carta The Birth of Liberty by Dan Jones
Magna Carta The Birth of Liberty by Dan Jones


The First Barons’ War: A Kingdom in Turmoil

The First Barons’ War (1215–1217) was a tumultuous civil war that erupted in the Kingdom of England. At its heart, a group of rebellious major landowners, known as barons and led by Robert Fitzwalter, took up arms against King John of England.

Origins of Conflict

The seeds of this conflict were sown by King John’s disastrous wars against King Philip II of France. These wars led to the collapse of the Angevin Empire, leaving John weakened and desperate. In an attempt to quell the rising discontent, John sealed the Magna Carta on 15 June 1215, promising reform but soon reneging on his commitments.

The Barons’ Rebellion

Faced with an uncompromising and deceitful king, the barons sought help from outside. They turned to King Philip’s son, Louis, who, in 1216, sailed to England with an army. This bold move defied both his father and the Pope, who excommunicated him for his actions. Louis quickly captured Winchester and controlled over half of the English kingdom. In London, the barons proclaimed him “King of England,” though he was never crowned.

A Turn of Fortunes

Louis’s ambitions took a major hit in October 1216 when King John died unexpectedly. This sudden event caused many rebellious barons to switch their allegiance to John’s nine-year-old son, Henry III. The war dragged on, but the tide turned decisively against Louis.

The Battle of Lincoln and Treaty of Lambeth

On 20 May 1217, Louis’s forces suffered a crushing defeat at the Battle of Lincoln. Adding to his woes, a fleet assembled by his wife, Blanche of Castile, was defeated off the coast of Sandwich on 24 August 1217, preventing much-needed reinforcements from reaching him. Cornered and outmanoeuvred, Louis was forced to make peace on English terms.

The Treaty of Lambeth, which he signed, compelled Louis to surrender the few remaining castles he held and acknowledge that he had never been the legitimate king of England. This treaty marked the formal end of the civil war and the departure of the French from English soil.


The Seal of Rebellion

In June 1215, a beleaguered King John faced a formidable alliance of powerful barons. Frustrated by his failed leadership and despotic rule, these barons forced John to affix his seal to a pivotal document known as “The Articles of the Barons.” On 15 June 1215, the king’s Great Seal marked the agreement. In return, the barons renewed their oaths of fealty to King John on 19 July 1215. By 15 July, the royal chancery formalised this accord in a document that would become renowned as the original Magna Carta.

The Law of the Land

One of the Magna Carta’s most enduring principles is encapsulated in the phrase “the law of the land,” standing in stark opposition to the king’s arbitrary will. The document contained clauses aimed at significantly curtailing royal power. Notably, Clause 61, known as the “security clause,” allowed a group of 25 barons to override the king by force if necessary. This medieval legal process, called distraint, was common in feudal relationships but unprecedented in its application to a reigning monarch.

From Negotiation to Warfare

The summer of 1215 saw a brief and half-hearted attempt at negotiation between the rebel barons and the king. However, these efforts quickly disintegrated, giving way to open warfare. The realm was plunged into conflict as the barons and the king’s supporters took up arms, marking the beginning of a turbulent chapter in England’s history.


French Intervention

The war began over the Magna Carta but quickly escalated into a dynastic struggle for the English throne. The rebel barons, unable to subdue a powerful King John, turned to Louis, son of King Philip II of France and grandson-in-law of King Henry II of England. Despite the historic Norman invasion, the relationship between England and France was not as adversarial as it would later become. The Annals of Waverley noted that Louis was invited to invade to prevent the realm from being pillaged by foreigners.

Initially, in November 1215, Louis sent a contingent of knights to protect London. However, he soon agreed to a full invasion, despite opposition from his father and Pope Innocent III. In May 1216, Louis’s troops disembarked on the coast of Kent, detected by watchmen on the coast of Thanet.

March to London

King John fled to Winchester, leaving Louis little resistance as he marched to London. Louis was received warmly by the rebel barons and citizens and proclaimed (though not crowned) king at St Paul’s Cathedral. Nobles, including Alexander II of Scotland, paid homage to him.

Many of John’s supporters, sensing the tide was turning, joined the barons. Gerald of Wales remarked, “The madness of slavery is over, the time of liberty has been granted, English necks are free from the yoke.”

Campaigns and Sieges

On 6 June, Louis pursued John south from London, capturing Guildford Castle on 8 June and Farnham Castle soon after. He faced resistance at Winchester Castle, which fell after a ten-day siege. By July, about a third of England was under Louis’s control.

First Siege of Dover

Louis’s father taunted him for not seizing Dover, England’s key port. Despite controlling most of Kent, Louis’s siege of Dover Castle in July 1216 was repelled by its constable, Hubert de Burgh, and a well-supplied garrison. After three months, Louis called a truce and returned to London.

Sieges of Windsor and Rochester

Windsor Castle held out against Louis with 60 loyalist knights surviving a two-month siege. Rochester Castle, repaired by John in 1206, was besieged by John in October 1215. The defenders held out despite severe tactics, including the use of pig fat to burn supports. The castle fell on 30 November due to starvation, not force.

Death of King John

On 18 October 1216, John contracted dysentery and died at Newark Castle. His death shifted the conflict’s focus. Louis now appeared a greater threat than John’s nine-year-old son, Henry.

Coronation of Henry III

Pierre des Roches and several barons crowned Henry at Gloucester Abbey on 28 October 1216, with a papal legate presiding. Magna Carta was reissued in Henry’s name, sealing it with the promise of rule by its principles.

Louis’s Decline

William Marshal gradually turned barons to Henry’s side. Louis captured Hertford and Berkhamsted Castles but faced resistance in Kent and Sussex. His reinforcement fleet was destroyed at the Battle of Sandwich, severely weakening his position.

Final Defeats

Louis faced further defeats at Lincoln and the Straits of Dover. By May 1217, his forces were severely diminished, leading to his eventual withdrawal and the end of the First Barons’ War.

Defection and Defeat

After a year and a half of war, the tide began to turn. Most of the rebellious barons had defected, abandoning their cause. This shift and the French defeat in 1217 left Louis with little choice but to negotiate. Some of Henry’s staunch supporters demanded unconditional surrender, but the Earl of Pembroke advocated for more moderate terms, aiming for a stable peace.


Source: (History’s Life Stories, 2022)


  • Jones, D. (2015). Magna Carta: The birth of liberty. Viking.‌

  • Wikipedia Contributors. (2024, May 18). First Barons’ War. Wikipedia; Wikimedia Foundation.

  • History’s Life Stories. (2022). King John of England, the Life & Death of this Medieval Monarch, First Barons War [YouTube Video]. In YouTube.


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