Answer:
The House of Representatives impeached Andrew Johnson over the Tenure of Office Act.
Explanation:
The Impeachment of Andrew Johnson, the seventeenth President of the United States, was one of the most dramatic political events in American history, going on during the Reconstruction era. This was the first impeachment (although partial, as the president was eventually acquitted) of a serving president in the United States, which was the culmination of a long battle between Johnson and the Republicans on how best to combat southern states after the Civil War.
Johnson was impeached on February 24, 1868 by the United States House of Representatives with justification in the "high crimes and contraventions" law, according to Article Two of the Constitution. Specifically, the House accused him of violating the 1867 Tenure of Office Act (which stated that certain occupants of Executive Office posts could only be removed with Senate consent). He had removed Edwin M. Stanton, then Secretary of War, from his position and replaced him with General Lorenzo Thomas, without consulting the upper house of Congress.
On March 13, 1868, the impeachment trial began in the United States Senate, being chaired by Chief Justice Salmon P. Chase. At the end of May, after the last attempt, the vote ended with 35 votes of "guilty" and 19 of "innocent". As it required 36 votes for impeachment (or two-thirds of the senators), the president was formally acquitted.
