Andrew Johnson’s impeachment was a result of political conflict and the split of ideologies that happened after the American Civil War. It arose from uncompromised beliefs and a contest for power in a nation struggling with reunification.

Before Lincoln was assassinated in 1865, he formulated a plan of reconstruction that would be lenient toward the South as it rejoined the Union. He planned to grant general amnesty to those who pledged an oath of loyalty to the U.S. and agreed to obey all federal slavery laws.

His 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 the state could formulate a new government and start sending representatives to Congress. Johnson was intent on carrying out Lincoln’s plan when he assumed the presidency. This policy did not sit well with the 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 the Congress.

Lincoln and Johnson had experienced problems with Stanton, an ally of the Radicals in Congress. Stanton’s removal 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. Johnson believed the Tenure of Office Act was unconstitutional and wanted it to be legally tried in the courts.

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 Johnson.

In a 1926 case, the Supreme Court declared the Tenure of Office Act had been invalid.

Source: Why was Andrew Johnson Impeached?
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