Hello there! Do you know what pirates are? They are people who steal things from other ships in the sea. Sometimes they pretend to be nice and friendly, but then they attack and take all the valuable things from the other ship. That's really mean, isn't it?
So, in the olden days, some countries wanted to catch the pirates and make them pay for all the bad things they did. But it was not always easy because the pirates were fast and tricky. So, the countries thought of a way to catch the pirates more easily.
They came up with an idea of giving special papers called "Letter of Marque" to some people. These people were called "privateers" and they were like pirate-hunters. The Letter of Marque was like a permission slip given by the government to the privateers. It said that the privateer could attack and capture pirates from other countries and take their valuable things like gold, silver, and treasure. So the privateers would get rich while also helping their country catch pirates.
But wait, is it allowed to attack and steal from others just because they are pirates? Isn't that still stealing? Well, that's a tricky question. The country that gave the Letter of Marque thought that pirates were dangerous and bad people who had to be punished. So it was okay for their privateers to attack and capture them. But other countries might not agree and think that the privateers themselves were the bad ones.
In any case, getting a Letter of Marque was a good deal for privateers because they could become rich and famous by catching pirates. But it was also dangerous because the pirates might fight back and the privateer could get hurt or even die.
So, that's what a Letter of Marque is. It's like a special paper that gave people permission to attack pirates and take their treasure. It was a way for countries to catch pirates more easily and punish them for doing bad things.