A more thorough explanation:

Marque is an old-fashioned word that means "reprisal." It refers to a license called "letters of marque" that allowed a private citizen to take revenge against citizens or ships of another country. This license was granted by the government of a country to its citizens.

For example, if a citizen of one country was mistreated by another country, the government of the first country might give that citizen letters of marque. This would allow the citizen to take revenge against the people or ships of the second country. This could mean seizing their property or attacking their ships.

However, this practice is no longer used. The United States government has not granted letters of marque since the 19th century.

One example of letters of marque being used was during the American Revolution. The Continental Congress granted letters of marque to American privateers. These privateers were authorized to attack British ships and seize their cargo. This was a way for the Americans to weaken the British economy and gain an advantage in the war.

Another example of letters of marque being used was during the Napoleonic Wars. The British government granted letters of marque to British privateers. These privateers were authorized to attack French ships and seize their cargo. This was a way for the British to weaken the French economy and gain an advantage in the war.

These examples illustrate how letters of marque were used in the past to allow private citizens to take revenge against other countries. However, this practice is no longer used because it is considered illegal under international law.