Although it was late in the campaigning season when he had come to power, Pitt set about trying to initiate a more assertive strategy. He conspired with a number of figures to persuade the Hanoverians to revoke the Convention and re-enter the war on Britain's side, which they did in late 1757. He also put into practice a scheme of Naval Descents that would make amphibious landings on the French coast. The first of these, the Raid on Rochefort, took place in September but was not a success. The centrepiece of the campaign in North America, an expedition to capture Louisbourg, was aborted due to the presence of a large French fleet and a gale that scattered the British fleet.