Early 1971: The Christian Democratic Party, which controlled the Chilean Senate at the time, passed a constitutional amendment requiring any constitutional changes to be passed with the approval of a two-thirds vote. This made it difficult for Allende's government to implement the reforms it wanted to make, as the opposition parties controlled more than a third of the votes.
May: Allende's government nationalizes the copper industry, angering the United States, which had significant investments in the industry and considered the move to be an illegal expropriation.
June: Allende visits Cuba and meets with Fidel Castro. This further strains relations with the United States, which fears the spread of communism in the Western Hemisphere.
August: The Chilean Constitutional Court rules that the nationalization of the copper industry is constitutional, but the Supreme Court later overturns the ruling, setting the stage for a crisis between Allende's government and the judiciary.
September 11: Allende's supporters hold a rally in Santiago to commemorate the first anniversary of his election. The rally is marked by violence, as police clash with protesters.
October: The Chilean Congress passes a law limiting the powers of the President, further weakening Allende's government.
November: The Chilean Navy revolts against Allende's government, but the revolt is quickly crushed.
December: The Chilean economy begins to deteriorate, as inflation and unemployment rise. The United States covertly provides financial assistance to Allende's opponents, aiming to destabilize his government.