July 7, 1865: four accomplices of John Wilkes Booth - George Atzerodt, David Herold, Lewis Powell, and Mary Surratt are executed by hanging at the Old Penitentiary in Washington, for their part in the assassination conspiracy. 
We should have more history in schools
I try
May God have mercy on their souls
I never knew it was a conspiracy until I read "Killing Lincoln" by Bill O'Reilly.
Makemeaspark: That book isn't bad. Manhunt is really good