Former British Prime Minister Margaret Thatcher, who died Monday, altered the course of post-war Europe. As the leader of the Conservative Party, she liberalized the British economy, ultimately forcing Britain's Labour Party to the political center and irreversibly remaking the country's political landscape. Meanwhile, she consolidated in her own party a determined skepticism of European integration, setting the stage for the U.K.'s ongoing efforts to keep its distance from the European Union. Finally, she set a gold standard for Anglo-American relations, forging a close relationship with President Ronald Reagan. Teamwork between London and Washington helped guide the Cold War to a peaceful end.