The first British major success of World War two was when Royal Navy forced the preying pocket Battle ship the Graf Spee, to scuttle at seaHitler had ordered a blockade of the British Isles and for some months German U-boats and warships caused havoc among allied merchant shipping carrying vital supplies. In 1941 the one sided battle of the Atlantic became more even, when the Royal Navy started moving ships in convoy with escorts using radar, and information from British scientists who had cracked the Kreigsmarine version of the Enigma Code captured by the Royal Navy. The perils of the Atlantic were only equalled by the Convoys on the run to northern Russia. Sub-zero temperatures, pack ice and appalling weather conditions plus the menacing Luftwaffe and the German Navy based in Norway, made it one of the most hazardous actions of the entire war. Meanwhile, in the air, bomber planes of the RAF and US air force were incessantly bombarding German Industries and cities. Casualties on the ground were devastating and the life expectancy of the aircrew was alarmingly short. The destruction of communications and armament factories was the main contribution from the bombing campaign.