letter of marque
letters of marque
letter of mark and reprisal

Her letter of marque was issued on 7 September 1793.

In 1807 she was either broken up, or became a letter of marque.

And by the way, partner, I really appreciate your not telling me about that letter of marque.

You have a good fast ship and a letter of marque.

"I thought the letter of marque would give you some legitimacy, but apparently not."

"It's been against our policy to accept letters of marque."

She said not to worry about your letter of marque.

He claimed her to be a Portuguese letter of marque.

She appears to have twice sailed under a letter of marque.

She received her second letter of marque on 30 July 1798.