The correct statement is: Johnson was impeached, but Congress was not able to remove him from office because of a lack of supporting votes.
President Andrew Johnson was impeached by the House of Representatives in 1868, primarily over his violation of the Tenure of Office Act. However, he was acquitted by the Senate, falling just one vote short of the two-thirds majority needed for removal from office. Johnson did not resign before the impeachment process; he completed his term.