Andrew Johnson has never ranked among America's most famous presidents, though he's widely considered one of the worst.
He's now attracting a surge of attention, as historians and political pundits compare his impeachment trial in 1868 with the ongoing impeachment inquiry targeting President Donald Trump.
Johnson barely escaped removal from office after his Senate trial, but was so disgraced he was denied his party's nomination that year.
The Democrat became vice president under Republican Abraham Lincoln on a unity ticket during Lincoln's reelection campaign amid the Civil War in 1864. Johnson became president after Lincoln's assassination.
Friction grew between Johnson, who contended blacks were incapable of self-government, and many of the Republicans who controlled Congress and favored extending voting rights to blacks. Tensions peaked after he fired his war secretary.