From Freeman Dyson’s description, the firestorms caused by strategic bombing were essentially “lucky” — from the bombers’ perspective:
For a week after I arrived at the ORS, the attacks on Hamburg continued. The second, on July 27, raised a firestorm that devastated the central part of the city and killed about 40,000 people. We succeeded in raising firestorms only twice, once in Hamburg and once more in Dresden in 1945, where between 25,000 and 60,000 people perished (the numbers are still debated). The Germans had good air raid shelters and warning systems and did what they were told. As a result, only a few thousand people were killed in a typical major attack. But when there was a firestorm, people were asphyxiated or roasted inside their shelters, and the number killed was more than 10 times greater. Every time Bomber Command attacked a city, we were trying to raise a firestorm, but we never learnt why we so seldom succeeded. Probably a firestorm could happen only when three things occurred together: first, a high concentration of old buildings at the target site; second, an attack with a high density of incendiary bombs in the target’s central area; and, third, an atmospheric instability. When the combination of these three things was just right, the flames and the winds produced a blazing hurricane. The same thing happened one night in Tokyo in March 1945 and once more at Hiroshima the following August. The Tokyo firestorm was the biggest, killing perhaps 100,000 people.The third Hamburg raid was on the night of July 29, and the fourth on August 2. After the firestorm, the law of diminishing returns was operating. The fourth attack was a fiasco, with high and heavy clouds over the city and bombs scattered over the countryside. Our bomber losses were rising, close to 4 percent for the third attack and a little over 4 percent for the fourth. The Germans had learnt quickly how to deal with WINDOW. Since they could no longer track individual bombers with radar, they guided their fighters into the bomber stream and let them find their own targets. Within a month, loss rates were back at the 5 percent level, and WINDOW was no longer saving lives.
The morality of fire-bombing was an open question, colored by the previous war:
While the attacks on oil plants were helping to win the War, Sir Arthur continued to order major attacks on cities, including the attack on Dresden on the night of February 13, 1945. The Dresden attack became famous because it caused a firestorm and killed a large number of civilians, many of them refugees fleeing from the Russian armies that were overrunning Pomerania and Silesia. It caused some people in Britain to question the morality of continuing the wholesale slaughter of civilian populations when the War was almost over. Some of us were sickened by Sir Arthur’s unrelenting ferocity. But our feelings of revulsion after the Dresden attack were not widely shared. The British public at that time still had bitter memories of World War I, when German armies brought untold misery and destruction to other people’s countries, but German civilians never suffered the horrors of war in their own homes. The British mostly supported Sir Arthur’s ruthless bombing of cities, not because they believed that it was militarily necessary, but because they felt it was teaching German civilians a good lesson. This time, the German civilians were finally feeling the pain of war on their own skins.I remember arguing about the morality of city bombing with the wife of a senior air force officer, after we heard the results of the Dresden attack. She was a well-educated and intelligent woman who worked part-time for the ORS. I asked her whether she really believed that it was right to kill German women and babies in large numbers at that late stage of the War. She answered, “Oh yes. It is good to kill the babies especially. I am not thinking of this war but of the next one, 20 years from now. The next time the Germans start a war and we have to fight them, those babies will be the soldiers.” After fighting Germans for ten years, four in the first war and six in the second, we had become almost as bloody-minded as Sir Arthur.
At last, at the end of April 1945, the order went out to the squadrons to stop offensive operations. Then the order went out to fill the bomb bays of our bombers with food packages to be delivered to the starving population of the Netherlands. I happened to be at one of the 3 Group bases at the time and watched the crews happily taking off on their last mission of the War, not to kill people but to feed them.