In the first few months of the war, Germany still hoped to persuade Britain to agree to peace. Although London hospitals prepared for 300,000 casualties in the first week, Germany unexpectedly did not immediately attack British cities by air, and German pilots that attacked Scottish naval bases said that they would have been court-martialled and executed for bombing civilians. Both sides found that attacks on military targets, such as a British attack on Kiel on the second night of the war, led to high losses of aircraft. They also feared retaliation for bombing civilians. (Britain and France did not realise that Germany used 90% of its frontline aircraft during the Polish invasion.) Civilian attitudes in Britain to their German foes were still not as intense as they were to become after the Blitz. On 30 April 1940, a German Heinkel 111 bomber crashed at Clacton-on-Sea in Essex, killing its crew and injuring 160 people on the ground. The crew were laid to rest in the local cemetery with support from the Royal Air Force. Wreaths with messages of sympathy were displayed on the coffins. British pilots mapped the Siegfried Line while German troops waved at them.