Britain now stood alone. Opinion was not unanimously in favour of continuing the fight against such unlikely odds. Some leaders suggested that Lloyd George should negotiate a settlement with Hitler. But Churchill, the new prime minister, ignored the German overtures. The future of the free world hung on his determination. The old warrior relied on American support and on the resources of the Commonwealth to unify the British people. He galvanized them with his energy. Even so it was by no means certain that the British had the means to hold out. The Royal Navy was strong enough to prevent an enemy landing, although the Norwegian campaign had shown that the most powerful battleships were vulnerable to attack. But the Norwegian campaign had also strained the German navy, which admitted that it could not now support a landing. Hitler renounced plans for invasion while Goering braced himself to tip the balance with the Luftwaffe. In the summer of 1940 a remarkable series of aerial battles began. Quite without precedent, this phase of the war came to be known as the Battle of Britain. Thanks to radar, a technical advance of which Britain then enjoyed a monopoly, and thanks to the superiority of the British fighter planes, the British were able to inflict heavy losses on the German air force. Much to everyone's surprise, the Germans were forced to abandon the strategy of destroying the Royal Air Force and its airfields, and turned to indiscriminate bombing of cities, especially London, in the vain hope of breaking British morale.