Was Henry III the worst king in medieval history? Our expert uncovers one of England's most disastrous reigns

Speaking on an episode of the HistoryExtra podcast, Foddy explains how Henry’s poor leadership, disastrous foreign policy and failure to control his own barons led to one of the most turbulent periods in English history – culminating in a full-scale rebellion and civil war.

A king without money - and a court full of enemies

Henry III was just nine years old when he inherited the throne in 1216, following the death of his infamous father, King John, whose tenure was plagued by military failures (including losing control of Normandy to France), heavy taxation and disputes with the Church.

Initially, the young Henry’s reign was stabilised by formidable advisors – men such as William Marshal, one of medieval England’s most celebrated knights. However, once Henry took full control of the levers of power, his poor financial management and erratic leadership alienated many of the realm’s most powerful nobles.

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According to Foddy, Henry’s “wasteful spending and high taxation” – combined with a harsh famine in 1257–58 – proved to be the final straw. The barons’ patience snapped and they moved against the king, forcing him to relinquish his power.

Foddy states: “Rather than just ruling himself and being the sole decision-maker, Henry now had to rule in partnership with a council. This had never been done before. It was a palace coup, and Henry couldn’t really say no.”

For the first time in English history, a king was no longer ruling alone. His decisions had to be approved by others, turning the monarchy into a shared government.

For the barons, this was a victory for reform. For Henry, it was a public humiliation. But this wasn’t an isolated moment: it was the culmination of a series of failures that included Henry’s botched vision of conquering Sicily.

Henry’s doomed dream of conquering Sicily

One of Henry III’s most spectacular failures was his attempt to claim the Kingdom of Sicily in the 1250s.

The pope had offered Henry’s younger son, Edmund, the Sicilian crown. But there was a catch: Henry had to finance the military campaign himself. Desperate for prestige and to forge a legacy, he agreed. However, as Foddy explains, “This obviously required a lot of money and effort – and Henry’s barons recognised that it was never going to happen.”

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Henry spent a fortune preparing for the invasion, but it ended in disaster. The campaign collapsed, wasting enormous sums of money and embarrassing him on the international stage. His barons were furious. For them, this was yet another example of the king’s poor judgement.

By 1258, Henry had lost so much trust that his own nobles forced him to give up power.

England descends into civil war

Henry III spent the next few years trying to restore his authority, but his refusal to accept limitations on his power led to open conflict.

“This was a radical moment,” says Foddy. “By 1264, civil war had erupted.”

The Second Barons' War (1264–67) was a bloody and brutal conflict between Henry’s forces and the rebel barons, led by the charismatic Simon de Montfort.

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For a time, the rebels controlled England, and de Montfort even set up a revolutionary government – one that gave a greater role to parliament. But in 1265, Henry’s son, the future Edward I, led a counterattack. De Montfort was slain on the battlefield, his body mutilated by royalist forces. With de Montfort’s death, Henry’s power was restored – but he had his son to thank for it.

Despite ruling for more than half a century, Henry III is often remembered as a king who mismanaged money, presided over a disastrous foreign policy, and was overthrown by his own barons.

And, in the end, Henry’s reign was salvaged not by his own leadership qualities, but by the military skills of Edward I. Unlike his father, Edward was an able and ruthless king who reasserted royal authority, crushed rebellions and built a more stable monarchy.

So, was Henry III England’s worst medieval king? He wasn’t the most hated – that title might belong to King John. But few medieval kings lost control of their own destinies quite as spectacularly as Henry did.