In the Timeless Universe
In the original timeline, Atzerodt goes to Johnson's hotel with the intention to assassinate the vice president, but couldn't work up the courage to go through with the plan. Instead, Atzerodt got drunk at the hotel. Atzerodt was executed on July 7, 1865 for his involvement with the conspiracy, along with other conspirators (including Lewis Powell).
George Atzerodt at Wikipedia