Elizabeth I had a glorious reign, but her beginnings were anything but. As an epoch-making monarch, she cannily managed a dangerous schism between Catholics and Protestants, defeated the Spanish Armada, presided over a cultural boon, enriched her country — and herself. Yet when Elizabeth took the throne in 1558, the prospect of triumphant reign was a dim one at best.

Daughter of the despised Anne Boleyn and an unhappy reminder of her mother’s ill-fated union with Henry VIII, Elizabeth not only had to contend with the skepticism of her doubters, but with a country scarred by religious disputes, famine, and poverty. It could have all gone very badly, but by the end of Elizabeth’s rule, England was a world power set on a path to empire. How did she do it? In “The Pirate Queen” (HarperCollins, 373 pages, $26.95) the historian Susan Ronald turns to the commercial exploits of sea dogs such as Sir Francis Drake, who made a mint attacking Spanish shipping, for an answer.

Although Ms. Ronald regales us with plenty of swashbuckling, her book isn’t merely a treatment for an Errol Flynn film. She has a thesis to advance. What undergirded the derring-do of Drake, Martin Frobisher, Walter Raleigh, and others was Elizabeth’s obsession with — echoes of our own time — security. Elizabeth’s dual quest for her own personal security and the security of the English state, argues Ms. Ronald, is a key to understanding a crucial phase in British history: “Elizabeth’s overpowering desire to be personally secure and to secure the safety of her people and realm,” Ms. Roland writes,

was the driving force behind her sanctioning of plunder, promotion of trade, switching allegiances, and eventually giving in to the imperial aims of her intellectuals and adventurers, and creating a nascent British Empire.

It’s a pretty sweeping statement, and Ms. Ronald perhaps bundles too much into the claim. As a stylist, she relies on clichés (“bigger fish to fry”) but her grasp of the complexities of the period is impressive. Above all, the ruthless Elizabeth was a survivor — she fended off court conspiracies, Catholic intrigues, and the all-powerful King Philip II and his Spanish Empire, which was her biggest headache. England had lost its main export market at Calais to the French, and Elizabeth looked overseas to the New World for opportunities to bolster her cash-poor coffers. Philip forbade trading with non-Spanish shipping, but the English pressed on anyway. The age of “hostile commerce” had begun.

Elizabeth turned to powerful business interests in London to finance a series of voyages that would mark the rise of England, which lagged far behind Spain, Portugal, and Venice as a commercial power. The meat of Ms. Ronald’s book is her account of the breathtaking journeys of Elizabeth’s pirate adventurers, who relentlessly provoked the Spanish. John Hawkins, “the queen’s most colorful corsair of the 1560s,” infuriated Philip by selling slaves on the cheap to Spanish colonialists, who were only too happy with the bargain the maverick Englishman offered.

The queen received a cut of each mission — Hawkins, for example, returned with ships overflowing with pearls, gold, silver, hides and sugar — and soon her treasury was flush with cash. As Ms. Ronald notes, the line between piracy and trade was a thin one; in reality, it was a free-for-all on the high seas.

For my money, the most illustrious figure of the time was the Spanish-hating champion of the Protestants, Drake. Drake found the luster of gold irresistible. He sailed with impunity through Spanish waters, besting all who challenged him. In 1572, he raided the key Spanish port of Nombre de Dios on the Panamanian coast, which he dubbed “the treasure house of the world.” He wasn’t kidding; from here flowed the gold and silver that underwrote Philip’s empire. Drake lurked offshore, capturing 12 vessels worth some $18 million in today’s currency. But this couldn’t be passed off as trade at all — it was outright piracy. (By this time, the Vatican, which wanted her head, had taken to calling Elizabeth “the pirate queen.”)

Drake dominated the era. Between 1577 and 1580, he circumnavigated the globe, which brought him even more fame. Most of the seas were uncharted, so Drake was sailing into the unknown. Ms. Ronald likens one stretch of the voyage, a 9,700-mile passage from Java to Sierra Leone, “to being launched to the moon out of a cannon, orbiting without instruments or ground control, then returning safely home.” When Drake sailed up the Thames, he was given a hero’s welcome.

Chasing doubloons, Drake and Company brought glory and revenue to England, and their piratical feats transformed England into an international power. Elizabeth knew that the oceans were the key to securing her kingdom against the Spanish. As Raleigh mused, “Whosoever commands the sea commands the trade; whosoever commands the trade of the world commands the riches of the world, and consequently the world itself.” It was a script that England would follow for 300 years.

Mr. Price last wrote for these pages on Jenny Uglow’s biography of Thomas Bewick.