Few figures in twentieth century history aroused as much enmity and admiration as Margaret Thatcher, who died at the age of 87. "The Lady's not for turning," she declared, and, for the most part, she was not. The high points of her tenure were breaking the 1984 National Union of Miners strike, winning the 1982 Falklands War, keeping Britain out of the Euro, and, not least, recognizing that Mikhail Gorbachev was the real thing. But then again so was the Iron Lady who snubbed the British establishment—the ultimate boys club—to climb to the top of the greasy pole.

When Thatcher became prime minister in 1979, Britain—a swan's nest in an English lake, as Shakespeare put it—had been stripped of its empire, its self-confidence. Thatcher—and Thatcherism—sought to revive what could be revived. To a large extent, Thatcher set the stage for the boom that took place under Tony Blair, though the current downturns that England is experiencing have reemboldened her critics to charge that her legacy was toxic. But Thatcher didn't just have beliefs. She had convictions. In his important new book Strange Rebels, Christian Caryl notes that Thatcher devoted great energy to studying classic texts about economics, that she loved to debate ideas, that she would, more often than not, wipe the floor with her opponents, and that it was "the force of her drive to realize her radically conservative ideas that made her unique."

She was not the greatest prime minister in British history, a claim that even she, who had fallen prey to hubris in her final years at Downing Street, probably would not have advanced. But she was the first great Tory Prime Minister since the incomparable Winston Churchill and certainly one of the most formidable. By the mid-1970s, Great Britain had become a calamitous mess. England, once a byword for gleaming efficiency, had become sunk in sloth and ennui. The miners didn't mine. Teachers didn't teach. Workers didn't work—unemployment had reached 2 million. Manufacturing output had plummeted by about 16 percent in 1980 alone.

Into this morass strode one Margaret Thatcher, determined to restore not only economic liberty but also traditional morals. Her determination impressed even her most ardent detractors. In his memoir, for example, the late Christopher Hitchens recounted that in the late 1970s, the "worst of 'Thatcherism,' as I was beginning by degrees to discover, was the rodent slowly stirring in my viscera: the uneasy but unbanishable feeling that on some essential matters she might be right." The tough economic medicine she administered—cuts in public spending—unsettled the Tory wets. Rather than try to placate them, Thatcher mocked them at a 1980 Tory party conference, where she told them they could cut and run, but she would not.

What might she have been right about? For one thing, she went about selling state-owned enterprises such as the British Gas and British Telecom. She refused to accept that the state, and the state alone, had a responsiblity to shore up faltering businesses or to keep the population on the dole permanently. Instead, she stressed thrift and hard work. She was also interested in ideas—ideas about private enterprise, liberty, morality. She refused to accept that Great Britain was a spent force. Instead, she argued that it could become great again, partly by maintaining its distance from the European Union.

In the long sweep of the twentieth century, she, together with Ronald Reagan, exercised a decisive impact on the fortunes of the West, both in domestic and foreign policy. When it counted, she also bucked up George H.W. Bush, telling him not to "go wobbly" in facing down Saddam Hussein during the first Gulf War. Thatcher is perhaps best-known in America as a cold warrior who was vigilant in warning about the Soviet threat. But she was also the first to declare that she could "do business" with Mikhail Gorbachev, then a young, by Kremlin standards, reformer who ended up demolishing the Soviet system of government. One of the few to pick up on the centrality of Thatcher's stance toward the Soviet Union is the Los Angeles Times, which notes "it was Thatcher who heralded his rise as more than another new face on a failed ideology. She urged President Reagan to give Gorbachev a chance to make good on pledges to stand down from the nuclear face-off and work for a less confrontational relationship between the superpowers." Together with Reagan, she helped to wind down the cold war that both had done much to fight. It was a great act of statesmanship.

So was a Thatcher a realist? No doubt her great mistake after the Cold War ended was to oppose German reunification. Here she was stuck in the past. But once again, her concerns were rooted in a balance of power. She had fought to preserve Britain's reputation and credibility and honor in the Falklands War. So, too, she tried in vain to persuade France's Francois Mitterand that they should together oppose the rise of a new and united Germany. She failed. She never seems to have lost her antipathy toward the Germans, the notion that they were itching for a fresh try to subjugate the continent and England. She was wrong.

But her overall record suggests a fairly pragmatic record when it comes to foreign policy. Thatcher left an indelible mark not only on England, but also the rest of the world. Perhaps her true proteges now reside in Beijing, where a kind of unbridled capitalism reigns that even she could never have reintroduced to the United Kingdom. Thatcher's economic legacy is once again the subject of debate, particularly in England, where the battles over the implications of her tenure have never really ended. But no one can dispute that she made the free market, not socialism, the center of that dispute. Thatcher may be gone, but not Thatcherism.