Margaret Thatcher, Britain's Iron Lady, Dead at 87

April 8, 2013 — -- Margaret Thatcher, the first woman ever to serve as prime minister of Great Britain and the longest-serving British prime minister of the 20th century, has died at age 87.

"It is with great sadness that Mark and Carol Thatcher announced that their mother Baroness Thatcher died peacefully following a stroke this morning," Lord Timothy Bell, her former adviser, said today. "A further statement will be made later."

Thatcher had significant health problems in her later years, suffering several small strokes and, according to her daughter, struggling with dementia.

In December 2012, she was underwent an operation to remove a bladder growth, longtime adviser Tim Bell told The Associated Press.

But during her long career on the political stage, Thatcher was known as the Iron Lady. She led Great Britain as prime minister from 1979 to 1990, a champion of free-market policies and adversary of the Soviet Union.

PHOTOS: Margaret Thatcher Through The Years

Many considered her Britain's Ronald Reagan. Indeed, Reagan and Thatcher were political soul mates. Reagan called her the "best man in England" and she called him "the second most important man in my life."

The two shared a hatred of communism and a passion for small government. What America knew as "Reaganomics" is still called "Thatcherism" in Britain.

Like Reagan, Thatcher was an outsider in the old boys' club. Just as it was unlikely for an actor to lead the Republicans, the party of Lincoln, it was unthinkable that a grocer's daughter could lead the Conservatives, the party of Churchill and William Pitt -- that is, until Thatcher. She led the Conservatives from 1975 to 1990, the only woman ever to do so.

Personal Life

Thatcher was born Margaret Hilda Roberts Oct. 13, 1925 in Grantham, England. She attended Somerville College, Oxford, where she studied chemistry and, later, in 1953, qualified as a barrister, specializing in tax issues.

She married Denis Thatcher Dec. 13, 1951, and their marriage lasted for nearly 52 years until his death in June 2003. The couple had twins, Mark and Carol, in 1953.

When Thatcher was elected to Britain's House of Commons in 1959, she was its youngest female member. In 1970, when the Conservatives took power, she was made Britain's secretary of state for education and science. In 1975, she was chosen to lead the Conservatives, and she became the prime minister in 1979.

WATCH: May 4, 1979: Margaret Thatcher Becomes Prime Minister

Her policies were controversial. She took on the nation's labor unions, forcing coal miners to return to work after a year on strike.

"We should back the workers and not the shirkers," she said in May 1978.

She pushed for privatization, lower taxes and deregulation. And she sought to keep Britain from surrendering any of its sovereignty to the European Union.

Full Coverage: Margaret Thatcher

Thatcher's admirers say she rejuvenated Britain's faltering economy. Her critics say the rich got richer and the poor were left behind.

In the inner cities, Thatcherism brought a violent backlash. There were calls from her own party to change course.

But Thatcher resisted.

"You turn if you want to," she said in October 1980. "The lady's not for turning."

She had courage in abundance. In 1982, when Argentina invaded the Falkland Islands, she took Britain to war -- and won.

In 1984, she narrowly escaped being killed when the IRA bombed her hotel during a party conference. The morning after, she convened the conference on schedule -- undaunted.