Henry V: The king who almost united England and France

A determined medieval knight in battle-worn armor stares intensely.
An imaginative digital depiction of Henry V in armour. © History Skills

The Hundred Years’ War produced no shortage of ambitious leaders, but few matched the combination of focus and fortune found in a single English king.

 

When he emerged from the long shadow of his father’s troubled reign, Henry V seized the opportunity to define himself primarily as a unifier rather than a warrior.

 

He looked across the Channel at opportunities where victories on the battlefield were meant to secure peace at the negotiating table. 

Securing Authority and Reviving Claims

Upon his accession to the English throne in 1413, Henry V inherited a troubled kingdom still scarred by the political strife of his father's reign.

 

His father, Henry IV, had deposed Richard II in 1399 and faced repeated rebellions, including the powerful Percy uprisings, the 1403 rebellion at Shrewsbury, the revolt led by Archbishop Scrope, and the ongoing threat of Welsh resistance under Owain Glyndŵr.

 

These internal challenges had drained royal resources and strained the legitimacy of the Lancastrian dynasty.

 

From the outset of his reign, Henry sought to secure his authority through a careful plan to strengthen his rule at home and prepare for conquest abroad. 

When he reinforced law and order, removed political rivals, and restored confidence in the monarchy, Henry established himself as a capable and commanding ruler.

 

He reconciled with former adversaries, reformed the royal council, and ensured a smooth transition of power.

 

Once domestic stability had been achieved, he revived the long-standing English claim to the French throne, first asserted by Edward III during the early stages of the Hundred Years’ War.

 

Henry viewed this as both a right based on his family claim and a means to unify his kingdom around a shared national cause.

 

In 1415, he began a campaign that would define his kingship. 


Harfleur and the Triumph at Agincourt

During the invasion of France that year, Henry’s decision to besiege Harfleur demonstrated strategic daring and skill in managing supplies.

 

The siege lasted from 18 August to 22 September 1415 and resulted in the fall of the deep-water port after long resistance.

 

Though the victory provided a crucial base of operations in Normandy, the English army suffered heavily from dysentery.

 

Because he was determined to return to Calais before the onset of winter, Henry led his army on a dangerous march across northern France.

 

At Agincourt on 25 October 1415, he confronted a much larger French force under the command of Charles d’Albret.

 

With an estimated 6,000 to 9,000 men, Henry faced a French army that may have numbered between 12,000 and 25,000.

 

When they combined disciplined formations with judicious positioning, his longbowmen acted with lethal efficiency; Henry won a crushing victory.

 

The French suffered severe losses among their nobility, including three dukes, nine counts, and over 100 other nobles.

 

English casualties were minimal. The triumph at Agincourt enhanced Henry’s reputation and strengthened his negotiating position in subsequent negotiations. 


Conquest of Normandy and the Treaty of Troyes

Following this success, Henry pursued an ongoing campaign of conquest in Normandy between 1417 and 1419.

 

His forces captured Caen, Bayeux, and other key towns before advancing on Rouen, the capital of the duchy.

 

The siege of Rouen, which lasted from July 1418 to January 1419, tested the endurance and resolve of both sides.

 

Henry’s blockade cut off supplies and caused widespread starvation and the deaths of thousands of civilians, with some chroniclers estimating as many as 12,000.

 

He refused to allow women and children to pass through the lines, a controversial decision that reflected his firm commitment to victory.

 

When the city surrendered, the victory established complete English control over Normandy for the first time in decades.

 

By occupying the duchy and securing its allegiance, Henry reasserted the Plantagenet claim with a strength not seen since the early fourteenth century. 

The political consequences of these military victories culminated in the Treaty of Troyes in 1420.

 

Under its terms, Charles VI of France recognised Henry as his heir and regent. The treaty disinherited the Dauphin, Charles VII, and arranged for Henry to marry Charles VI’s daughter, Catherine of Valois.

 

The marriage, which took place at Troyes Cathedral on 2 June 1420, provided a direct dynastic link between the two crowns.

 

Because Charles VI suffered from periodic insanity and the French court was divided between the Armagnac and Burgundian factions, Henry’s position appeared secure.

 

The assassination of John the Fearless in 1419 had driven the Burgundians into alliance with England, a development which helped secure the treaty.

 

The agreement made the union of crowns official in principle, though enforcement relied on continued military control and support from French allies. 


Henry's Final Campaign and Death

During the final years of his life, Henry worked to strengthen his authority in both kingdoms.

 

He travelled widely through France and strengthened garrisons while collecting oaths of loyalty and negotiating with French nobles.

 

He also returned to England to secure parliamentary approval for continued taxation and to maintain order.

 

In 1421, Catherine gave birth to a son, Henry of Windsor, who offered a future of the royal line that could tie both domains together.

 

However, renewed fighting soon disrupted this unstable balance. 

The Dauphin refused to accept the Treaty of Troyes and continued to resist from southern France.

 

In 1422, Henry returned to the continent to stop uprisings and reinforce English positions.

 

He led a siege of Meaux, a key town east of Paris held by Armagnac loyalists. The siege lasted several months and exposed Henry to the harsh winter and the worst of disease.

 

He died on 31 August 1422 at Vincennes at the age of thirty-five after he had become exhausted and suffered from illness.

 

Less than two months later, Charles VI also died, meaning that the infant Henry VI, only nine months old, became king of both England and France under the terms of the treaty. 


Collapse of the Dual Monarchy

Despite the formal unification of the two crowns, the situation quickly got worse.

 

Henry VI’s weak government proved ineffective, and French resistance under Joan of Arc and other commanders won back territory.

 

In 1429, Joan famously lifted the siege of Orléans and paved the way for Charles VII’s coronation at Reims.

 

The union that Henry V had fought to create fell apart as the French gradually expelled the English from their possessions.

 

By October 1453, with the fall of Bordeaux, England kept only Calais on the continent. The dream of a dual monarchy had collapsed. 

Henry V came closer than any English king to achieving a lasting union between England and France.

 

He imposed strict military discipline and asserted his personal authority through skilled negotiations which almost turned a claim into lasting reality.

 

His early death removed the only figure capable of enforcing the treaty, and the fragile agreement he secured fell apart under the weight of French nationalism and English internal divisions.

 

The vision of a united Anglo-French domain died with him, but his achievements left a lasting impression on both countries’ histories.

 

Shakespeare’s portrayal of him in the late sixteenth century ensured that his reputation endured well beyond the battlefield.