A double POD - but both on April 14, 18654, might do it - Grant decides to accompany LIncoln to Ford's Theater, and the guy sent to kill Andrew Jhonson decided not to get drunk.
Except that had Grant also been at the threatre, the sentry would have been unlikely to leave his post, so they both survive, rather than dying.
April 1965?
April 14, 18654