The impeachment of President Andrew Johnson was the result of political conflict and the rupture of ideologies in the aftermath of the American Civil War. It arose from uncompromised beliefs and a contest for power in a nation struggling with reunification.
"Sir, the bloody and untilled fields of the ten unreconstructed States, the unsheeted ghosts of the two thousand murdered negroes in Texas, cry...for the punishment of Andrew Johnson."- Rep. William D. Kelley, calling for impeachment of Andrew Johnson
Before Abraham Lincoln was assassinated in 1865, he had formulated a plan of reconstruction that would be lenient toward the defeated South as it rejoined the Union. He planned to grant a general amnesty to those who pledged an oath of loyalty to the United States and agreed to obey all federal laws pertaining to slavery (though high-ranking Confederate officials and military leaders were to be excluded from the general amnesty).
Lincoln's plan also stated that when a tenth of the voters who had taken part in the 1860 election had agreed to the oath within a particular state, then that state could formulate a new government and start sending representatives to Congress.
Andrew Johnson was intent on carrying out this plan when he assumed the presidency. This policy, however, did not sit well with the so-called Radical Republicans in Congress, who wanted to set up military governments and implement more stringent terms for readmission for the seceded states. As neither side was willing to compromise, a clash of wills ensued.
The political backing to begin impeachment proceedings against the president came when Johnson breached the Tenure of Office Act by removing Edwin Stanton, Secretary of War, from the cabinet. The Tenure of Office Act, passed over Johnson's veto in 1867, stated that a president could not dismiss appointed officials without the consent of Congress.
Both Lincoln and Johnson had experienced problems with Stanton, an ally of the Radicals in Congress. Stanton's removal, therefore, was not only a political decision made to relieve the discord between the president and his cabinet, but a test of the Tenure of Office Act as well. Johnson believed the Tenure of Office Act was unconstitutional and wanted it to be legally tried in the courts. It was the president, himself, however, who was brought to trial.
President Johnson was impeached by the House of Representatives on February 24, 1868 and the Senate tried the case in a trial that lasted from March to May 1868. In the end, the Senate voted to acquit President Andrew Johnson by a margin of 35 guilty to 19 not guilty - one vote short of the two-thirds needed to convict.
In a 1926 case, the Supreme Court declared that the Tenure of Office Act had been invalid.