Congress has attempted to impeach several presidents over the years: John Tyler in 1843, James Buchanan in 1860, Andrew Johnson in 1868, Richard Nixon in 1974, William Clinton in 1998 and George W. Bush in 2008. Only two were actually impeached and the other attempts withered on the Congressional vine.
Andrew Johnson, who disobeyed the Tenure of Office Act by firing a Cabinet member without Congress’ approval and William Clinton who committed perjury and obstructed justice were the two who were impeached. Nixon likely would have been impeached, but he resigned.
Neither of the two who were impeached were convicted and both remained in office even though it was evident that they did indeed commit “high crimes.”
The latest attempt at impeachment of a president is now in progress, sort of. If impeachment of President Trump goes forward, it appears that it will be in response to his “high crime” of getting elected as president of the United States.