The Morality (or Otherwise) of the Allied Bomber Offensive

Effectiveness?
The idea was to kill their workers and shut down their factories.

It certainly had a big impact, once accuracy had improved.

The effectiveness of Allied bombing of Germany is dubious. Certainly, British night raid area bombing designed primarily to damage German civilian morale, was ineffective. And the British themselves should have known this from their own experience. After all, when the Germans bombed the hell out of British civilian areas, rather than causing a collapse of morale it tended to harden civilian determination to resist, as well as fuelling a desire to give the same back. This latter made the bomber chiefs, particularly Arthur Harris in charge of Bomber Command from early 1942, highly popular figures for giving the Germans a taste of their own medicine. But there was a general conceit in the higher echelons that German morale would crack when British morale hadnt under similar attacks. In fact it was even less likely in Germany since it's government was a dictatorial one less vulnerable to public opinion.

The Americans of course joined the strategic bombing campaign in 1942 but at first their raids were fairly small scale and not until the latter half of 1943 were they starting to approach British levels in bombing intensity. The Americans believed in precision attacks in daylight and that their bombers were so heavily armed that they could effectively defend themselves against fighters. Initially until their crews gained experience they attacked easier coastal targets mostly in France. But once they began to undertake daylight raids deep into Germany they experienced devastating and insupportable losses. So their own bombing efforts were for these reasons little more effective than Britain's.

But things changed drastically in the Allies favour in 1944. The first class American fighter, the mustang, began to be equipped with extra fuel drop tanks, enabling them to escort bombers right into the heart of Germany. American raids continued to suffer heavily for a time, but at the cost of the Luftwaffe being shot out of the skies over Germany itself. This also resulted in the withdrawal of German fighters from the fighting fronts to be gradually destroyed in the skies over Germany, which gifted the allies total air superiority over the fighting fronts, greatly hindering German supplies and movement in daylight.

The long range mustang also allowed for precision attacks deep in the heart of Germany and the key thing was the Americans singling out of transportation and oil production targets. The latter in particular resulted in the near collapse of the supply of fuel to mechanised German forces which proved disastrous for German mobility. From the summer of 1944 onwards, there were increasing instances of German tanks and other vehicles which were in perfectly good order having to be destroyed because they lacked the fuel to move them back away from advancing enemy forces.

However, it remains the case that until the advent of the long range mustang and the precision attacks on oil targets this allowed, the Allied bomber offensive was ineffective and costly to the attackers, and motivated primarily in Britain itself by a desire to inflict payback for the blitz.