“The U.S. House of Representatives votes 11 articles of impeachment against President Andrew Johnson, nine of which cite Johnson’s removal of Secretary of War Edwin M. Stanton, a violation of the Tenure of Office Act. The House vote made President Johnson the first president to be impeached in U.S. history.”
More, see: https://www.history.com/this-day-in-history/president-andrew-johnson-impeached