The article is devoted to the unknown page of the European diplomatic history of the XVIII century. The French annexation of Corsica in 1768 produced a serious crisis in the Anglo-French relations. Corsica's location in the western Mediterranean, close to the great southern naval base at Toulon, gave it considerable strategic importance for France. The head of the French cabinet Duke de Choiseul had always shown an interest in securing the control over the island. In 1768 favorable international conditions for fulfillment that aim took place. But Choiseul feared that Britain would oppose any annexation and might even launch a preventive war. The French minister tried to maintain absolute secrecy during the intensive negotiations with Genoa, which led, by the Treaty of Versailles signed on 15 May 1768, to France's thinly disguised purchase of the island at a bargain price. The English government gradually realized the full extent of Choiseul's plans, but the official British response was notably weak. Choiseul's strategy of presenting Britain with a fait accompli secured a notable success