1961: Appointed a deputy minister for Pensions and National Insurance, serving until 1964.
1970: Appointed education secretary in the Cabinet of Conservative Prime Minister Edward Heath, serving until 1974.
Feb. 11, 1975: Defeats Heath in a contest for leadership of the Conservative Party, then in opposition.
May 4, 1979: Becomes prime minister when Conservatives win a parliamentary majority in the general election.
April 2, 1982: Argentine forces invade the Falkland Islands, claiming the British colony as their own. Britain sends a naval task force and reclaims the South Atlantic islands June 14-15 after the Argentines surrender. The war costs 255 British lives and 650 Argentine lives.
July 9, 1982: Begins second term as prime minister after the Conservatives win a general election.
March 12, 1984: The National Union of Mineworkers, opposing plans to close 20 unprofitable mines, begins a strike that lasts 51 weeks -- the longest and most violent strike in British history and a watershed in Thatcher's effort to crush union power.
Oct. 12, 1984: Escapes injury when the Irish Republican Army detonates bomb at her hotel in Brighton during a Conservative Party conference. Five people are killed and 31 injured.
March 3, 1985: Miners vote to return to work without a settlement.
Jan. 6, 1986: Defense Secretary Michael Heseltine resigns from the Cabinet in a dispute over the American-led takeover of British Westland PLC helicopter manufacturer. Heseltine sought a British-European rescue bid.
June 11, 1987: Leads Conservatives to an election victory, becoming the only prime minister of the 20th century to win three elections consecutively.
Oct. 26, 1989: Nigel Lawson, chancellor of the exchequer, resigns following conflicts over monetary policy.
Nov. 1, 1990: Deputy prime minister Sir Geoffrey Howe, a former foreign secretary and the last of Thatcher's original Cabinet, resigns over the prime minister's stance toward European union.
Nov. 13, 1990: Howe tells the House of Commons that Thatcher is jeopardizing vital British intertests and dividing the government.
Nov. 14, 1990: Michael Heseltine declares his challenge for leadership of the party and the prime minister's job -- Thatcher's first serious challenger after 15 years at the helm of the party and 11 in power.
Nov. 20, 1990: Conservatives in the House of Commons hold a leadership election. Heseltine forces Thatcher into a second-round ballot, scheduled for Nov. 27.
Yesterday: Thatcher resigns, saying her departure would serve the interests of party unity and improve the prospects for a Conservative Party victory in a general election. SOURCES: The Washington Post; Associated Press