He was a celebrated soldier, a hero on land and sea. He was responsible for the first ever English colonies in the New World. And he wrote poetry that ranks with some of the finest in early modern England. Yet at the age of 66 Sir Walter Raleigh was executed for treason. What caused the downfall of this beloved Renaissance courtier?

For a court favorite, Raleigh actually spent quite a bit of his life locked up in the Tower of London. The first time, in 1592, it was because he’d secretly married his lover, Elizabeth ‘Bess’ Throckmorton, a lady-in-waiting to Elizabeth I. Bess was already pregnant, which explained both the marriage and the secrecy. Enraged by their plotting behind her back, Elizabeth dismissed Bess and imprisoned both of them in the Tower.

Much popular history, including the film_, Elizabeth: The Golden Age_, has tried to explain this punishment by imagining that the queen was in love with Raleigh. However, this is no evidence for this. Rather, Elizabeth’s anger was justified: for young nobles like Bess who were sent to the royal household the monarch became a kind of surrogate parent, expected to supervise their upbringing and encourage lucrative marriages with other influential nobility. For the couple to ignore the queen’s prerogative here was scandalous.

Nevertheless they were soon released and in a few short years Raleigh had regained the queen’s favor. She awarded him a royal charter to explore the ‘New World’ of the Americas and allowed him to organize the first English colonies in Virginia, named flatteringly after the Virgin Queen herself. That these colonial experiments were an unmitigated disaster, resulting in the ‘Lost Colony’ of Roanoke, did not dissuade Raleigh and his backers from believing that fortunes lay in the Americas.

He was convinced that El Dorado, the legendary city of gold, was to be found in northern South America, and made a reconnaissance trip to Guyana in 1595. On his return he wrote a fantastical account of it as a paradise rich for the taking, where gold could be plucked easily from the ground, and where the natives were eager to be ruled over by the English. This ridiculous propaganda would tempt more than one monarch to allow Raleigh to travel there in England’s name.

While he remained in Elizabeth’s favor until her death, James VI’s of Scotland’s accession to the English throne as James I meant that Raleigh’s fortunes plummeted. This was largely because James was attempting a diplomatic rapprochement with Spain, England’s longstanding enemy, against whom Raleigh had been a formidable foe. England’s funds were depleted by their endless struggles against Spain’s richer, mightier forces, so James decided it was time to end the rivalry.

The real crisis for Raleigh came when he was falsely implicated in a plot to oust the new king. Called the Main Plot, its aim was to replace James with his cousin Lady Arabella Stuart. The allegation was that Henry Brooke, Lord Cobham, was negotiating with a Dutch prince to have the Spanish give him huge sums of money to foment sedition in England. Cobham was to bring the money back via the Channel Island of Jersey, where Raleigh was governor, and together they would use it to overthrow the king.

The claims were ludicrous and based entirely on the word of Cobham, who never testified in front of Raleigh. As for Raleigh, no man in England had made a larger contribution to England’s war with Spain, so the charge that he accepted funds from the Spanish to undermine England’s crown strained credulity.

But James, in his determination to get on Spain’s good side, locked up Raleigh once again in the Tower—this time for 13 years. Although Raleigh had been given a death sentence, his time in the Tower wasn’t quite as bad as it might sound: the aristocracy were imprisoned there because its conditions were much better than in the other prisons of early modern England, where ‘gaol fever’—or typhus—ran rampant. Raleigh lived with Bess there, and she even conceived a son while they were inside.

It was likely Raleigh’s promises of gold that got him released from prison before his sentence could be carried out: in 1617 he was pardoned so that he could once again travel to Guyana in search of El Dorado. But that quest would ultimately prove fatal: during the expedition a detachment of Raleigh’s men (against his orders) attacked a Spanish outpost, an action that directly contravened the conditions of his pardon.

Upon Raleigh's return, the Spanish ambassador, Count Gondomar, demanded that his death sentence from 1603 be reinstated. James had little choice but to obey. On October 29, 1618, a full 15 years after he had been convicted of treason in a sham trial, the famous explorer was beheaded at Whitechapel in London.

In the end, it seems Raleigh’s reputation as Spain’s greatest foe was what undid him: the Spanish were eager to see the downfall of one who had won so many victories against them. Unlike all the legends about him— he didn’t introduce tobacco or the potato to England, nor place his cloak over a puddle for the queen—his reputation as a heroic soldier was, for once, justified.