Andrew Johnson in Reconstruction
Andrew Johnson (1808–1875) became America's 17th president in April 1865, upon the death of Abraham Lincoln. Though most people recognize that Congress fabricated the charges against him, Johnson was the first ever to be impeached by the House of Representatives, and missed removal from office by one Senate vote. He's generally identified as one of the worst presidents in American history.
A spokesman for the non-slaveholding white majority in Tennessee, Johnson was the only Southern representative to remain in Congress after his state seceded in June 1861. He vigorously supported the Lincoln administration and was named Lincoln's running mate on a unity platform in the election of 1864. After he ascended to the presidency, Johnson seemed poised to enact retribution on the slaveholding aristocracy that he'd long resented. Instead, his lenient Presidential Reconstruction program merely issued thousands of pardons to the wealthiest landowners and infuriated Congress, which rejected his plan and refused to seat the newly elected Southern representatives.
In February 1868, the Republican majority in Congress impeached Johnson for violating the Tenure of Office Act. Johnson had rightly suspected Secretary of War Edwin M. Stanton of conspiring with congressional leaders, and had forced him out of office, but the Tenure of Office Act mandated that he seek the advice, consent, and approval of the Senate to remove a federal officeholder. The Supreme Court later declared the act unconstitutional in 1926.