Robert Curthose’s Failed Invasion of England and the Treaty of Alton (1100–1101)

Following the death of William Rufus on August 2, 1100, Ranulf Flambard, the notorious financial adviser to both William the Conqueror and William Rufus, encouraged Robert Curthose to claim the English throne. Robert, who was returning from the First Crusade, found himself outmaneuvered by his younger brother Henry, who seized the English crown before Robert could assert his claim. In 1101, Robert launched an invasion to reclaim England but failed due to poor strategy and lack of support, leading to the Treaty of Alton.

The Death of William Rufus and Henry’s Seizure of the Throne (1100)

• William Rufus died in a suspicious hunting accident in the New Forest on August 2, 1100.
• Robert was still returning from the Crusades, giving Henry the perfect opportunity to seize the throne of England before his elder brother could react.
• Henry moved swiftly, securing the royal treasury in Winchester and being crowned King of England on August 5, 1100.
• Meanwhile, Robert, still in Italy, was about to marry a wealthy bride to raise funds to buy back his duchy from Henry.

Robert’s Claim to the English Throne and the Invasion of 1101

• Upon his return to Normandy, Robert was urged by Ranulf Flambard and several Anglo-Norman barons to challenge Henry’s rule based on the short-lived 1087 agreement, which had designated Robert and William Rufus as each other’s heirs.
• In July 1101, Robert landed at Portsmouth with an army, intent on deposing Henry.
• However, Robert’s poor strategy and lack of support among the English nobility weakened his position.
• Unlike Henry, who had won over the English barons, Robert struggled to gain allies, and his invasion tactics were poorly executed.

The Treaty of Alton (1101): Robert’s Surrender

• Rather than engaging in a prolonged conflict, Robert was forced into negotiations with Henry.
• In the Treaty of Alton, Robert renounced his claim to the English throne in exchange for a pension of 3,000 marks a year and Henry’s promise of peace.
• This formally ended Robert’s ambitions for England, leaving him with only the Duchy of Normandy, which he continued to mismanage.

Robert’s Military and Political Failures

• Robert was known as a brilliant field commander but a terrible general, as seen in the First Crusade, where he showed great valor in battle but lacked leadership skills.
• His inability to govern Normandy effectively left the duchy in chaos, while his failed invasion of England demonstrated his lack of strategic acumen.
• Ultimately, Robert’s incompetence in both war and governance led to his eventual downfall at the hands of Henry I, who would conquer Normandy in 1106 at the Battle of Tinchebray.

Conclusion: Henry’s Triumph and Robert’s Decline

• The Treaty of Alton (1101) marked the failure of Robert’s final attempt to claim the English throne, ensuring that Henry I remained king.
• Robert’s poor political and military decision-making weakened his rule, setting the stage for his final defeat in 1106.
• Henry, in contrast, proved himself a far more effective ruler, consolidating Normandy and England under his firm control.

Robert’s 1101 invasion of England was his last major challenge to Henry I, and his defeat and subsequent downfall reflected his lifelong struggle with leadership and strategic planning.