MARQUE, or Letters of MARQUE, in war, are letters of reprisal, granting the subjects of one prince or state liberty to make reprisals on those of another. They are so called from the German marcke, limit, frontier, as being jus concessum in alterius principis marckas seu limites transeundi, sibi jus faciendo, or a right of passing the limits or frontiers of another prince, and doing one's self justice.