If these things had not happened on March 13 in the past, they might have made darned good scenarios.
1138: Cardinal Gregorio Conte is elected Antipope Victor IV, succeeding Anacletus II, which nowadays is making a comeback in an antibiotic-resistant form.
1639: Harvard College is renamed for John Harvard after he dies in 1638 and leaves them a bunch of books in his will. In 1884, a statue of John Harvard by MIT grad Daniel Chester French is dedicated in front of Memorial Hall. In 1920 French complains about the site of the statue and three years later it is moved in front of University Hall in Harvard Yard. The statue is known as "The Statue of the Three Lies," because of its inscription, "John Harvard – Founder – 1638." There was no likeness of John Harvard, so it's not him; Harvard did not found the college, it was merely renamed for him after his death; and the college was founded in 1636 (Harvard died in 1638).
1781: William Herschel discovers Uranus. (Insert your own or your seven year-old's joke here.)
1881: Tsar Alexander II is assassinated by a bomb-thrower in front of his palace after getting out of his bulletproof carriage against the advice of his security detail to investigate a previous bombing attempt. Let this be a lesson to all future tsars.
1962: The Chairman of the Joint Chiefs of Staff, Lyman Lemnitzer, presents perhaps the craziest plan ever proposed by the U.S. federal government to Secretary of Defense Robert McNamara. According to author James Bamford: "Operation Northwoods, which had the written approval of the Chairman and every member of the Joint Chiefs of Staff, called for innocent people to be shot on American streets; for boats carrying refugees fleeng Cuba to be sunk on the high seas; for a wave of violent terrorism to be launched in Washington, D.C., Miami, and elsewhere. People would be framed for bombings they did not commit; planes would be hijacked. Using phony evidence, all of it would be blamed on Castro, thus giving Lemnitzer and his cabal the excuse, as well as the public and international backing, they neeeded to launch their war." No record exists of the reaction of McNamara or President Kennedy to this proposal, but three days later, Kennedy told Lemnitzer that there was no chance of another attack on Cuba (after the Bay of Pigs invasion which Lemnitzer had also supported), and a few months later Lemnitzer was denied another term as Chairman of the Joint Chiefs of Staff.