Found after 300 years, the scourge of the British navy - This Britain, UK - The Independent With 25 guns and a plunder-thirsty crew, La Marquise de Tourny was the scourge of the British merchant fleet some 260 years ago. For up to a decade, the French frigate terrorised English ships by seizing their cargoes and crew under a form of state-sanctioned piracy designed to cripple British trade.