Donald Trump has become the first American president to be impeached twice, a week after violent protesters stormed the U.S. Capitol. Here are all the U.S. presidents who have previously been subject to impeachment proceedings:

• In 1868, Andrew Johnson, the 17th president, was accused of, among other things, dismissing his secretary of war against the will of Congress. Johnson had a narrow escape – the required two-thirds majority in the Senate was missed by just one vote.

• Richard Nixon, the 37th president, resigned in 1974 before he could be impeached over the Watergate scandal.

• Bill Clinton, the 42nd president, found himself impeached on the grounds of perjury and obstruction of justice after he lied about the nature of his affair with Monica Lewinsky and then allegedly asked her to lie about it as well. But when the trial reached the Senate in 1999, the vote for a conviction failed to get close to the two-thirds backing as required.

• President Donald Trump's first impeachment was initiated on December 18, 2019, when the House of Representatives approved articles of impeachment on charges of abuse of power and obstruction of Congress. The Senate acquitted Trump of these charges on February 5, 2020.