It's one of those moments in war where technology leaps ahead of international law. Additional Protocol I to the Geneva Conventions in 1977 outlawed the attack of "works or installations containing dangerous forces" to the civilian population [1]. You'd be very hard-pressed to argue it was illegal at the time. Whether it was immoral is, of course, up for debate!
Oh I agree with you. It is just that the dam busters raid was such a powerful propaganda piece - "English ingenuity over the Evil Empire" type thing, and I truly do admire the technical skills and bravery involved in the whole raid.
But the downvotes that my comment above (and no doubt this one) gets just exacerbates the whitewashing of Allied atrocities during WWII. Case in point:
"Bomber command lost nearly 50% of their crew during WWII" - "Oh dear that is terrible tragedy - upvotes for you, my friend for pointing out this invaluable fact."
"Lots of German civilians were killed in the floods after the Dambuster raid" - "Meh, who cares? Cost of war. Downvoted. NEXT!"
Yeah, I think it's pretty interesting to compare Germany with Japan in that case. Japanese cultural memory and historiography intensely remembers the suffering of civilians from famine, firebombing, and nuclear weapons [1] (but rarely from the military itself [2]), but even suggesting that German civilians suffered unnecessarily from strategic bombing in Der Brand (2002) earned Jörg Friedrich, a German historian of Nazi war crimes, widespread censure.
[1] Grave of the Fireflies is a gorgeous, heartbreaking film. Highly recommended!
Hmm. I suppose this would be unfair if it were just a case of "Allies won and Axis didn't, so let's tell Allied stories and not Axis ones."
But the Germans were aggressors in this case, whose democratically elected leader initiated and waged one of the most terrible wars that the world has ever seen. So maybe the reaction you're seeing is a result of that?
But hard pressed to argue that waging war against innocent civilians was against accepted ethics? I hardly think so. It was considered unacceptable by the civilized world in the 1930s[1]. WW II rapidly saw it become the norm, as tit-for-tat spread.
[1] https://ihl-databases.icrc.org/ihl/WebART/470-750071?OpenDoc...