‘They have sown the wind, and now they will reap the whirlwind’. With this grim warning, Air Marshal Sir Arthur ‘Bomber’ Harris, the head of the RAF’s Bomber Command vowed vengeance for Germany’s Blitz against Britain in 1940/41. He was as good as his word, squadrons of Wellington, Halifax, Sterling and finally the hugely successful Lancaster heavy bombers pounded German cities night after night with ever increasing power. The cost was high, German night-fighters and Flak ground defences meant that losses to aircrew were higher than in any other branch of the fighting forces. But the air offensive was highly popular in a country with few other means of hitting back at the enemy and few at the time questioned the morality of carpet bombing civilian targets. Technical advances enabled raids to be more targeted such as the famous Dam Busters attack. But with the USAF joining the offensive from 1942, the relentless attacks continued, and by the end of the war, most German cities were in smoking ruins. It is still hotly debated whether the air offensive materially shortened the war.