A model of medieval chivalry and modern commerce

At the hour of his execution, Sir Walter Raleigh ran his thumb along the blade of the headman's ax. "This is a sharp medicine but it is a physician for all diseases," he quipped to the assembled crowd. Such style partly explains why ever since his death in 1618, Raleigh, whether being portrayed as republican martyr or patriotic hero, has held a special place in the hearts of his countrymen. The truth, of course, is more complex. As Raleigh Trevelyan says in this nicely balanced new biography, "It is impossible to give an outright verdict on Raleigh."

Born into an old Devon family that had turned to privateering - a form of government-sanctioned piracy practiced by English adventurers against Spanish shipping - the young Raleigh was ambitious and bold. Fighting alongside relatives in the Huguenot wars in France and then serving the crown in Ireland during an uprising against English rule, he quickly distinguished himself as a confident and ruthless military leader.

Handsome and well-spoken, he managed to catch the eye of Queen Elizabeth, who took him into her intrigue-filled court as her newest favorite. There he prospered - "none of Raleigh's rivals could compete with his sycophantic versifying," writes Trevelyan - and prestigious appointments and lucrative monopolies followed.

Raleigh, however, was not looking for a comfortable sinecure. Eager to take risks, he raised financing for colonial expeditions to the New World. The first of these resulted in a small colony on Roanoke Island, although this was ultimately abandoned. Later, fired by Spanish rumors of a gold-laden El Dorado somewhere in Guiana, he led an expedition up the Orinoco River, but failed to discover any gold.

Glory - both his and his queen's - was a key motivator for Raleigh. At the battle of Cadiz, he and the other English commanders literally blocked each other's ships in order to ensure that their own would be the first in the heat of battle against the defending Spanish. And during an operation in the Canary Islands, Raleigh got fed up waiting for the Earl of Essex's ships to arrive and rowed ashore with his men to mount his own ground attack on a Spanish fort.

For profit and for glory: Raleigh seems an ideal representative of Elizabethan England, poised as it was between the not entirely complementary worlds of medieval chivalry and modern commerce.

Unfortunately for him, Raleigh also came to mark a junction between the arbitrary power of kings and the gradually strengthening rule of law. His rapid rise and proud manner gained him many enemies, and as Queen Elizabeth aged, thoughts of succession came to dominate the minds of senior courtiers. Raleigh made himself vulnerable by remaining aloof from the inevitable politicking, and by the time James VI of Scotland ascended the English throne, the king's mind had already been poisoned against Raleigh by the whispering of his enemies.

Put on trial on trumped-up charges of high treason, Raleigh defended himself brilliantly, but to no avail. Even he could not beat a system so stacked against the accused. Yet as Trevelyan concludes, his trial "was a first flicker in the change of attitude towards rights of individuals against the power of the mighty State."

His death sentence indefinitely postponed by the king, Raleigh was imprisoned in the Tower of London for 13 years, during which time he wrote the first massive volume of his History of the World. Finally, he was released to lead another expedition for Guyana's gold. He wasn't pardoned, though, and when the voyage ended in failure - including the loss of his eldest son and the unauthorized razing of a Spanish town - Raleigh was executed on the original treason charge to placate Spain.

Raleigh was regarded at first as merely an ambitious and ruthless courtier, but the intelligence and dignity he displayed at his trial and later execution led many to turn against King James's rule, and transformed contemporaries' views of Raleigh. On the day before his death, Raleigh ran into an old friend in the palace yard where his scaffold was being erected. The friend told him that he would attend his execution if he could find a place in the large crowd that was expected. "I do not know what you may do for a place," said Raleigh with a sardonic smile. "You must make what shift you can. But for my part, I am sure of one." His place on the scaffold was undeserved. His place in history was not.

• Ian Garrick Mason is a Toronto writer whose work appears in The Spectator and the San Francisco Chronicle.