On this day in 1967, Israeli air and naval forces attacked and destroyed an American warship in international waters without warning or provocation. In retaliation, the United States was minutes from launching a nuclear attack against Cairo, believing initially that it had been Egyptian forces which had launched the attack.
Whether you believe the Israeli account that this was simply the result of a series of tragic errors during the Six Day War, or believe those (including the USS Liberty sailors who survived the attack) who believe this was the result of a conspiracy between US and Israeli intelligence forces to blame Egypt and give America an excuse to enter the war, this is a pretty fascinating piece of recent military history that is rarely reported and not widely known. This 2002 BBC documentary tells the story well:
You can also visit the USS Liberty Memorial page to read an account from members of the Liberty’s crew.