LONDON — Success in the Falklands War set the stage for a pivotal fight with the National Union of Miners, which began a 51-week strike in March 1984 to oppose the government's plans to close a number of mines.
The miners battled police on picket lines but couldn't beat Thatcher, and returned to work without gaining any concessions.
She survived an audacious 1984 assassination attempt by the Irish Republican Army that nearly succeeded. The IRA detonated a bomb in her hotel in Brighton during a party conference, killing and injuring senior government figures, but leaving the prime minister and her husband unharmed.
Thatcher won a third term in another landslide in 1987, but may have become overconfident.
She trampled over cautionary advice from her own ministers in 1989 and 1990 by imposing a hugely controversial "community charge" tax that was quickly dubbed a "poll tax" by opponents. It was designed to move Britain away from a property tax and instead imposed a flat rate tax on every adult except for retirees and people who were registered unemployed.
That decision may have been a sign that hubris was undermining Thatcher's political acumen. Tens of thousands of protesters took to the streets in London and other cities, leading to some of the worst riots in the British capital for more than a century.
The shocking sight of Trafalgar Square turned into a smoldering battleground on March 31, 1990, helped convince many Conservative figures that Thatcher had stayed too long.
"How could a leader who was wise make 13 million people pay a tax they had never paid before? It just showed that she was no longer thinking in a rational way," one of her junior ministers, David Mellor, said in a BBC documentary.
For Conservatives in Parliament, it was a question of survival. They feared vengeful voters would turn them out of office at the next election, and for many that fear trumped any gratitude they might have felt for their longtime leader.