The Anarchy Civil War in Medieval England

Written by Simon Williams

In 1135, Stephen of Blois seized the English throne from its rightful heir, Empress Matilda, starting nineteen years of civil war. Neither side achieved decisive victory, and the conflict ended in 1153 when Henry II, Matilda’s son, was recognised as Stephen’s heir.

Key Facts

• Period: December 1135 to October 1154
• Claimants: Empress Matilda (Henry I’s daughter) and Stephen of Blois (Henry I’s nephew)
• Key victory: Battle of Lincoln, February 1141 (Matilda captures Stephen)
• Failed coronation: June 1141 (Matilda driven from London before crowning)
• Famous escape: Oxford Castle, winter 1142 (Matilda crossed the frozen Thames)
• Settlement: Treaty of Winchester, November 1153
• End of war: Henry II crowned 19 October 1154

The Anarchy is usually summarised in a sentence: Stephen seized the throne, Matilda fought back, chaos followed for nineteen years. That sentence is true but not much use if you actually want to understand how the war unfolded. This is the year by year record: what happened, when it happened, and why each turning point mattered. For the fuller political and thematic picture, including governance, the Church, and Matilda’s later career, see our comprehensive briefing on Empress Matilda and the Anarchy. For the case for Matilda’s own leadership and legacy specifically, see our profile of her rule, character and later influence.

1135: Stephen’s Coup

King Henry I died in Normandy on 1 December 1135, having named his daughter Matilda as his heir and forced his barons to swear oaths supporting her claim, twice. Matilda was in Anjou with her husband Geoffrey when the news reached her. Her cousin Stephen of Blois was not. He crossed the Channel within days, secured the royal treasury at Winchester, and was crowned King of England at Westminster before Matilda could organise a response. The oaths meant to guarantee her succession proved worthless the moment a faster claimant appeared.

1139: Matilda Invades

For nearly four years, Stephen ruled with enough competence to contain sporadic unrest, but his position was never fully secure. In 1139, Matilda crossed to England and landed at Arundel, backed by her half-brother Robert of Gloucester, one of the most capable military commanders of the period, and by her uncle King David I of Scotland, who invaded northern England on her behalf. The disputed succession had finally become open war.

1141: Lincoln, the Lady of the English, and the Rout of Winchester

February 1141 brought the single most dramatic reversal of the war. At the Battle of Lincoln, Matilda’s forces defeated and captured Stephen, imprisoning him at Bristol Castle. With her chief rival in chains, Matilda was acclaimed Domina Anglorum, Lady of the English, and travelled to London to prepare for her coronation.

It never happened. Matilda’s refusal to grant the tax concessions Londoners expected of a new ruler triggered an armed uprising that forced her to flee the city days before the ceremony. Her momentum collapsed further at the Rout of Winchester, where forces loyal to Stephen’s wife captured Robert of Gloucester. Matilda had no choice but to trade her prisoner for her general: Stephen was released in exchange for Robert, and the war reset to stalemate.

1142: The Siege of Oxford and the Years of Stalemate

The most famous single episode of the Anarchy came in the winter of 1142, when Stephen’s forces trapped Matilda inside Oxford Castle. Facing starvation after months under siege, Matilda escaped at night with a small party of knights, reportedly dressed in white to blend into the snow, crossing the frozen River Thames on foot before walking to safety at Abingdon.

The years that followed brought no decisive victory to either side. The war became a grinding contest of sieges rather than pitched battles, with castles changing hands repeatedly and neither claimant able to convert territorial gains into lasting political control. England’s central justice system effectively collapsed. Local lords built unauthorised castles, raised private armies, and, in the words of one contemporary chronicler, ruled as though Christ and his saints slept.

1147 to 1153: Henry Takes Up the Fight

The death of Robert of Gloucester in 1147 ended Matilda’s capacity to sustain the war in England directly. She withdrew to Normandy the following year, passing her claim to her son Henry Plantagenet, who was then only fifteen. By 1153, aged nineteen, Henry crossed to England with a force strong enough to renew the conflict in earnest, and this time the balance of power had shifted decisively in his favour.

1153 to 1154: The Treaty of Winchester and the End of the War

Rather than risk a battle he might lose, Stephen chose to negotiate. Extended mediation, led by the Church, produced the Treaty of Winchester in November 1153. Its terms were straightforward: Stephen would remain king for the rest of his life, and Henry would be recognised as his adopted heir. Stephen’s own son Eustace had died shortly before the treaty was agreed, removing the one obstacle that might have complicated the succession further.

Stephen died on 25 October 1154, and Henry II took the throne without contest, nineteen years after his mother’s claim had first been overturned.

What the Anarchy Left Behind

The war’s most immediate legacy was damage: to royal authority, to the treasury, to the coinage, and to a countryside that had absorbed two decades of intermittent violence. It took years for Henry II to rebuild the centralised government his grandfather had commanded. But the Anarchy also left a structural legacy that outlasted the destruction. The growth of baronial power during the conflict, and the concessions both claimants made to secure noble support, created tensions over royal prerogative that would resurface two generations later when King John’s barons forced him to seal Magna Carta. For the people who actually lived through it, the Anarchy was simply the moment when the machinery of English kingship stopped working. What came after was Henry II’s attempt to rebuild it, covered in full in our profile of Henry II’s reign and legal reforms.

This article is part of The Anarchy series. Explore all articles at The Anarchy.

Deepen Your Understanding

History rarely happens in isolation. The people, places, and events on this page are part of a much bigger story. The articles below trace the threads that connect to what you have just read; follow whichever pulls at your curiosity.

→ Empress Matilda and the Civil War in England: Away from the timeline: how Matilda actually governed, and why she spent thirteen years as Henry II’s most trusted adviser

→ Empress Matilda: The Woman Who Nearly Became England’s First Queen: The full biography of the woman at the heart of the civil war: her escape across a frozen river, her near-coronation, and the dynasty she built through sheer refusal to quit

→ Stephen of Blois: A Historical Overview: The man who started the Anarchy by seizing the crown, and why historians judge him so harshly

→ Empress Matilda and the Anarchy: A Comprehensive Briefing: A structured breakdown of every key event, turning point, and player in the nineteen-year conflict

→ Castles of Conflict: Fortresses of the Anarchy Era: How the desperate castle-building of the civil war years transformed English military architecture for generations

→ The Church and the Crown: Religion’s Role in the Anarchy: Why the shifting loyalty of bishops and abbots was as decisive as any battle

→ Henry II: A Monarch of Legal Reforms: The son Matilda fought for, and how he turned the chaos of the Anarchy into the foundations of English common law

People Also Ask

What caused the Anarchy in medieval England?

The Anarchy was caused by a succession crisis following the death of King Henry I in December 1135. Henry had designated his daughter Matilda as his heir and extracted sworn oaths of support from his barons, but these oaths proved worthless when his nephew Stephen of Blois moved faster. Stephen crossed to England within days of Henry’s death, secured the treasury at Winchester, and was crowned king before Matilda could organise a response. The underlying cause was a combination of the general reluctance of twelfth-century barons to accept female rule and the personal ambition of Stephen, who had both the proximity and the will to act.

What happened at the Battle of Lincoln in 1141?

The Battle of Lincoln, fought on 2 February 1141, was the defining military engagement of the Anarchy and its most dramatic turning point. Matilda’s forces, led by her half-brother Robert of Gloucester, surprised Stephen’s army at Lincoln and inflicted a decisive defeat. Stephen himself was captured during the battle and imprisoned at Bristol Castle. With her rival in chains, Matilda was acknowledged as Domina Anglorum, Lady of the English, and prepared to travel to London for her coronation as queen. However, her failure to secure the loyalty of Londoners led to her expulsion from the city before the ceremony could take place, and Stephen was eventually released in an exchange of prisoners.

How did Empress Matilda escape from Oxford Castle?

In the autumn of 1142, Stephen’s forces besieged Matilda inside Oxford Castle and held it under sustained pressure for months. Facing starvation, Matilda escaped in the winter of 1142 in dramatic fashion. According to contemporary accounts, she slipped out at night with a small escort of knights, reportedly wearing white cloaks to blend into the snow-covered landscape, and crossed the frozen River Thames on foot. She then made her way to Abingdon and from there to the safety of Wallingford Castle. The escape became one of the most celebrated moments of the entire conflict and contributed significantly to Matilda’s reputation for resourcefulness and determination.

What was the Treaty of Winchester?

The Treaty of Winchester, concluded in November 1153, was the agreement that ended the Anarchy. Negotiated under the mediation of the Church, principally Archbishop Theobald of Canterbury, it established that Stephen would remain king for the rest of his life, and that on his death the throne would pass to Matilda’s son, Henry Plantagenet. The death of Stephen’s own son Eustace earlier that year had removed the main obstacle to this settlement, as it freed Stephen from having to pass the crown to his own heir. Stephen died in October 1154, and Henry II took the throne without opposition, fulfilling the treaty’s terms exactly as agreed.

How did the Anarchy end?

The Anarchy ended through negotiation rather than military victory. By 1153, Henry Plantagenet had crossed to England with a strong force and won several significant engagements, but Stephen still held enough power to prolong the conflict. Both sides were exhausted, and the death of Stephen’s son Eustace had removed Stephen’s main incentive to fight on. With the Church mediating, the two sides concluded the Treaty of Winchester in November 1153, recognising Stephen as king for life and Henry as his successor. Stephen died the following October, and Henry II’s accession ended nineteen years of civil war without a further battle being fought.

What were the long-term effects of the Anarchy?

The Anarchy left England with weakened royal authority, a depleted treasury, debased coinage, and a baronage that had grown accustomed to acting independently during the years of competing claimants. Henry II spent much of his reign systematically restoring central government, reforming the legal system, and reasserting royal control over the church and the barons. The concessions both Stephen and Matilda had made to secure noble support created tensions that outlasted the conflict: the growth of baronial power that the Anarchy accelerated contributed to the political environment that produced Magna Carta in 1215, two generations later. The Anarchy also accelerated the construction of stone castles across England, transforming the country’s military architecture in ways that persisted for centuries.

Primary Sources and Further Reading

• The Gesta Stephani, an anonymous contemporary chronicle of Stephen’s reign, is the principal narrative source for the year-by-year course of the war.
• Henry of Huntingdon, Historia Anglorum, offers a further contemporary account, including the description of England as a land where "Christ and his saints slept".
• William of Malmesbury, Historia Novella (circa 1142), covers the war’s early years from a perspective sympathetic to Matilda.
• Edmund King, King Stephen (Yale University Press, 2010), is the authoritative modern narrative history of the reign and the civil war.
• David Crouch, The Reign of King Stephen, 1135 to 1154 (Routledge, 2000), provides a detailed year-by-year analysis of the conflict’s military and political course.

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