George Atzerodt. The night Abraham Lincoln was assassinated, Atzerodt had plans to assassinate Vice President Johnson. Atzerodt was an associate of John Wilkes Booth. Except after Atzerodt arrived at the hotel where Johnson was staying he didn't go upstairs; he stopped at the bar.
And got drunk instead.
The look on his face seems to summarize the man: intensely avoiding eye contact.
Lewis Powell have an informality that was rare for the era. Powell was twenty-one years old. He has the build of a college athlete, except the manacles are visible and he leans against the gun turret of a Monitor class warship. Powell had stabbed Secretary of State William Seward repeatedly in an attempted assassination. It was a lucky chance that Seward survived. When Powell assaulted Seward, Seward was bedridden and wore a neck brace. The brace prevented Powell's knife from reaching the jugular vein.
Two years later Seward organized the purchase of Alaska.
A neck brace and some drinks at a hotel bar changed history.
Powell is hard to crop. It's also difficult to select just one portrait; he's very natural in front of a camera. So I haven't worked on him yet. Maybe someone else will beat me to it. There are a lot of worthwhile images out there.