Intentionally targeting and executing civilians is not war, just plain murder. The Allies were guilty of this during WWII...
When it came to what they did to Germany and the Germans, the Allies were guilty of nothing in WWII.
Albert Speer on the "terror" bombing of Hamburg:
We were of the opinion that a rapid repetition of this type of attack upon another six German towns would inevitably cripple the will to sustain armament manufacture and war production. It was I who first verbally reported to the Fuehrer at that time that a continuation of these attacks might bring about a rapid end to the war."
Hamburg was bombed most heavily in July-August of 1943. We didn't go after another six towns rapidly. If you read Churchill's memoirs, many of his contemporaries lost their stomach for it after seeing what Operation Gomorrah did. Meanwhile, the Holocaust raged on for nearly another two years.
When you have a conflict you clearly need to win, you win it, and you wait until the end to feel bad about it.