France had opened the war against Britain in Europe by capturing Menorca and until 1759 they believed they held the upper hand. The British navy, however, had initiated a tight blockade of the French coast which prevented supplies and troops moving freely and sapped morale. Realizing that Prussia was unlikely to be defeated until its ally Britain was, the French foreign minister, Choiseul developed a plan to invade Britain in three separate places at Portsmouth, Essex and Scotland. He oversaw the construction of a massive fleet of transports to convey the troops during 1759. Defeats of the French navy at Lagos and Quiberon Bay put an end to these plans and he was forced to call off the invasion in the late autumn. A diversionary force under François Thurot had managed to land in Northern Ireland before he was hunted down and killed by the British navy. In the wake of the disaster at Quiberon, Thurot was lionised as a hero in France.