I want to start off by telling that this is not a hoax, this event has evidence that it actually happened in the past.

Ever wondered why it is called April "Fools" day but not April "Jokes" day? Here is the real deal.

At the late 15th century, Christian Crusaders besiege final castle of Muslims in Andalusia. Even though it was winter, castle was still safe, so the Crusaders' general was trying to develop a new tactic.

Finally, at night of 31th May, he aproached the castle with Bible on the one and Quran on the other hand, and he says that they won't hurt them in any way if they surrender. After meetings between two generals, and Muslims finally surrender so they won't get hurt anymore, since there was kids and women in the castle.

Next morning, general orders the army to execute everyone by cutting of their heads. While it was happening, people told the general that he sweared them to not hurt anyone, and he said "The promise was for evening of the day before, and i don't have any promises for today" then they all get executed.