I finished reading Impeached about 3 weeks ago and haven't written about it yet, which should tell you exactly how I felt about it. Andrew Johnson is that rare creature - a bad president who is also a boring president. Usually the bad presidents (Buchanan, Adams) are at least fun or educational to read about, and it's the ones whose administrations never get off the ground - your Martin Van Buren and your Franklin Pierce - that seem like a waste of time.
Part of the problem could be that this is the first non-biography I've read. Impeached is mainly an account of Johnson's impeachment trial, obviously, and spends just as much time on his critics as it does on him, because they were actually more involved in the trial than he was. With a traditional biography, I've usually built up some empathy for the presidents before they enter office, so that even if they are terrible I feel for them. But Impeached isn't about a journey to, through, and from the White House, it's about 4 horrible years.
[All this, of course, is neither a flaw or the fault of the book. I'm simply pointing out the differences in my reading experience.]
So, AJ was Lincoln's VP, chosen for that role (AS USUAL) unwisely (AS USUAL) because he was from the South. Did they really check to make sure he was down with Lincoln's policies? No. Did they check to see if he was even reeeeally a Republican? Also no. Did they check to make sure he wasn't a white supremacist? Hahahahaha. When he was sworn in as VP he was hammered, and delivered a long, unintelligible speech that made everyone embarrassed. He would repeat this performance a few years later, when he went on a stump speech tour of the Midwest, talking yards of nonsense at every stop and comparing himself to Jesus.
It would have been hard to fill Lincoln's shoes no matter what, but Johnson was bizarrely ill-qualified. The patient, conciliatory Unionist was replaced by an unreasonable bullhead. The first thing he did was decide that the recently freed slaves should be given neither citizenship nor voting rights. All the abolitionists, who had seen that as the end goal of the war, were like ummmmm wtf? They could expect support from the Republican president, but oh, Johnson had decided he wasn't a Republican anymore. No! He wanted to be a states rights "Jeffersonian." He vetoed the Civil Rights Bill, and all four of the Reconstruction Acts, although these five bills were all passed by a Congressional override. He was against the Fourteenth Amendment, which granted citizenship and federal rights to anyone born in American (except people born on Indian reservations, love you guys), but Congress wisely passed it by state ratification and joint resolution, so it wasn't subject to his veto.
He also disagreed with Republicans on what should be done with Confederate leaders. He didn't think that anyone who had served in the high ranks of the Confederate military or government should be punished in any way, opening the door for them to be reelected to the federal government. This put the fear of re-secession and another war into Republicans, but states rights what can you do?
The Republicans were just spitting mad, and kept writing impeachment articles. Many of them thought that Johnson was going to blindly steer the country right back into the 1850s and that they had to get rid of him in any way possible. The accusation - that he had fired Secretary of War Stanton in violation of the Tenure of Office Act (which they had recently passed) - was vague and purely political. Johnson's defense was that the Tenure of Office Act was unconstitutional and he didn't have to abide by it (which seems, in my opinion, to be true).
As the impeachment vote drew near, a black pastor prayed a public prayer for the conviction of "this demented Moses of Tennessee," which was my favorite part of the book. Johnson avoided impeachment by bribing lots of Senators.