04/08/2013 12:19 EDT | Updated 06/08/2013 05:12 EDT

Margaret Thatcher: 5 defining moments

Former British prime minister Margaret Thatcher, who died Monday at the age of 87, was a divisive but ultimately transformative figure in the country's politics.

- Margaret Thatcher, former U.K. PM, dead at 87

Known for her staunch pro-business stance and unbending will, the Iron Lady governed Britain during a time of great social, economic and labour unrest.

Here’s a look at five key moments in her political career.

'The lady's not for turning'

By the fall of 1980, the British economy had fallen into recession and more than two million Britons were unemployed. To stimulate growth, Thatcher advocated deregulation and privatization of many state industries. The opposition urged her to consider making a “U-turn” on these policies.

During a speech at the Conservative party congress on Oct. 10, 1980, Thatcher dug in her heels, with a phrase that would characterize her iron will. “To those waiting with bated breath for that favourite media catchphrase, the 'U-turn,' I have only one thing to say: 'You turn if you want to. The lady's not for turning.' "

The Falklands War

On Apr. 2, 1982, the military government in Argentina invaded the nearby Falkland Islands, a British territory that the South American country has long claimed as its own. Thatcher responded with overwhelming military force, and after a two-month battle, forced Argentina to surrender on June 14. The war took the lives of 255 British soldiers, as well as 649 Argentine military personnel. About half those deaths — 323 — were a result of the British torpedo attack on the Argentine cruiser the General Belgrano. Three Falkland residents were also killed in the conflict. The war demonstrated Thatcher's conviction, boosting her popularity back home and even helping in some way to lift the sagging economy.

1984 miners strike

In early 1984, the government proposed closing 20 of Britain’s 174 state-run coal mines, which would cut about 20,000 jobs. Two-thirds of the country’s miners protested. Determined to reduce the power of trade unions, Thatcher refused to bend, and when the National Union of Mineworkers (NUM), which represented coal miners, went on strike in 1984, she waited them out for an entire year. In March 1985, the NUM conceded, without a deal. The work stoppage cost the economy an estimated £1.5 million and put a significant dent in the value of the British pound.

Escapes IRA bomb attack

In 1984, Thatcher narrowly escaped being injured after the IRA planted a bomb at the hotel hosting the Conservative Party conference in Brighton. Five people were killed in the blast that went off just before 3 a.m. on Oct. 12. Another 34 were injured.

Thatcher's steeliness and defiance in the face of the attack won her praise and bolstered her reputation. She insisted that the conference open on schedule a few hours after the devasting explosion, and declared, "the fact that we are gathered here now — shocked, but composed and determined — is a sign not only that this attack has failed, but that all attempts to destroy democracy by terrorism will fail."

Her role with Soviets

Thatcher's political instincts had wide-ranging effects, including her conclusion early on that Soviet leader Mikhail Gorbachev represented a clear shift in the Soviet tradition of autocratic rulers. She said the West could "do business" with him, a position that influenced U.S. President Ronald Reagan's dealings with Gorbachev as the Soviet era declined.

In comments from his website reported Monday in the Daily Telegrah, Gorbachev said: "Our first meeting in 1984 set in train relations that were sometimes complicated, not always smooth, but which were serious and responsible on both sides. Human relations also gradually took shape, becoming more and more friendly.

"In the end we managed to achieve a mutual understanding, and that contributed to a change in the atmosphere between our country [the Soviet Union] and the West and the end of the Cold War."