Given the general inaccuracy of bombing and target identification, how would "sparing the city" be done? Perhaps if the B-17 and Lanc's were all carrying JDAMs we could hope for your hope, but without the GPS satellites in orbit, JDAMs are not much better than dumb bombs.
While it's certainly true that bombing in WW2 was by no means as accurate as what can be done today, there was a range of accuracy and this was quite well known. German air defenses were heavily degraded by Feb 45, and there was certainly a tradeoff between incinerating a city with fire bombs and creating a literal fire storm in the air, vs. targeting rail yards, airfields, factories and troop concentrations. As I see it, there were 4 options:
- Burn the city down with heavy bombers day and night and incinerate the civilians, friendly POW's, everybody
- Targeted bombing with escorted heavy and medium bombers during daytime only, to take out the larger more obvious targets (we had quite a few in operation by 1945)
- Use precision bombing with fast bombers like Mosquitoes, A-26s, maybe Bostons and Beaufighters
- Use fighter bombers as was done in Falaise etc.* Tempests, P-47s, P-51s
Any of the above would have caused fairly heavy civilian casualties,
some amount of casualties among Allied aircraft, and I think any of the above would also have been able to do the (military) job. The actual fire raid killed 20-30,000 people and destroyed the heart of a 700 year old city. B-17 daylight raids might have been 1/3 to 1/4 of that (of course, just a wild guess). Mosquito and fighter-bomber raids might have seen civilian deaths more like in the hundreds rather than the thousands, though Allied aircrew losses would have certainly been higher.
Personally I really like the Mosquito option though they weren't really being used that way at the time. They should have had a lot of them by 1945, I don't know the exact number in squadrons but they had made probably 6 or 7,000 by then. If you had say, 1,000 Mosquitos and 200 A-26s in a raid that could be pretty devastating. The actual firebombing included 750 Mustangs so you didn't need to make any changes to scare up a better escort. Throw in any P-47s and Tempests that had sufficient range (not sure about that part either) and I see it as a bad day for the Germans. Assuming you can find a clear day in February.
I concede that there were actual military targets there, but how much of the brutality of that raid was done to impress / scare the Soviets, how much due to doctrine by people like Harris or the USAAF bomber mafia guys, and how much was due to actual Operational reasons?
* yes I know they didn't get that many tanks with rockets and so on but they did effectively destroy the fighting capacity of that army