On this date in 1865, four confederate sympathizers convicted of participating in the conspiracy to assassinate President Lincoln (as well failed attempts to assassinate Vice President Andrew Johnson and Secretary of State William H. Seward) were executed by hanging in the Old Arsenal Penitentiary (now Fort McNair) in Washington, DC. The conspirators were Mary Suratt, Lewis Payne, David Herold, and George Atzerodt. Mary Suratt was the first woman executed by the US federal government.
Wikipedia – Assassination of Abraham Lincoln
A Little Touch of History – The Lincoln Conspirators Execution Photos