Margaret Thatcher, Britain's first woman prime minister, held the office for more than 11 years, including all of the 1980s. During that time, she left a major mark on U.S. politics, mainly through her close relationship with President Ronald Reagan.
Here's a look back at the five moments that stand out:
1. "The second most important man in my life." Bound by opposition to communism, Thatcher and Reagan shared a close bond throughout the 1980s. Together, they provided a united western counterbalance against the Soviet Union, and modernized Europe's anti-Soviet nuclear shield. Thatcher once referred to Reagan as the "second most important man" in her life.
2. Strains in the relationship: The Reagan-Thatcher relationship wasn't always so rosy. Reagan didn't immediately support Britain in its conflict with Argentina in the Falkland Islands in 1982, urging the European ally to pursue talks. And Thatcher's government denounced the Reagan-sanctioned invasion of Grenada in 1983.
Documents that were newly declassified in 2012 revealed some of the strains in the Thatcher-Reagan relationship. Thatcher once described a Reagan dispatch on the Falklands invasion as "so vague, I didn't think it was worth reading."
3. Address before a joint session of Congress: Thatcher addressed the U.S. Congress in 1985, winning rousing applause for a speech in which she vouched for the Reagan administration's foreign policies. "In an address that stirred applause in the packed House chamber -- especially among Republicans -- Mrs. Thatcher also stressed that she firmly supported President Reagan's space-based missile defense research plan," the New York Times reported at the time.
4) "No time to go wobbly." Toward the end of her tenure as prime minister, Thatcher helped spur on President George H.W. Bush to intervene militarily in the Persian Gulf after Saddam Hussein invaded Kuwait. Thatcher famously declared to the U.S. president that "this was not time to go wobbly."
Here's how Thatcher described her initial thoughts about Hussein's invasion of Kuwait, in an interview with PBS's "Frontline:" "I went out for a walk, always lovely in the mountains, and got things worked out in my mind, but it was perfectly clear, aggression must be stopped. That is the lesson of this century. And if an aggressor gets away with it, others will want to get away with it too, so he must be stopped, and turned back. You cannot gain from your aggression."
5) Spurning Sarah Palin: In 2011, the Guardian newspaper reported that Thatcher would not be meeting with Sarah Palin during Palin's trip to London. "Lady Thatcher will not be seeing Sarah Palin. That would be belittling for Margaret. Sarah Palin is nuts," the paper quoted one Thatcher ally as saying. The rejection sparked an outcry among conservatives in the United States, lending a great deal of attention to the non-meeting.