I would just like to point out that, despite our revisionist history that makes it look like we attacked Germany to save the Jews, it's important to keep in mind that the allies knew about the systemic attack on Jews before it ever progressed to the death camps, and did nothing. I'm not saying the allies didn't care, just that it wasn't the main priority for wanting to go on the offensive. There were even anti-semetic sections of the British and French media that were praising Hitler's work, especially because he was also actively exterminating religious enemies and homosexuals. There are even well-documented reports that the Catholic Church was involved in handing over Jews, and protecting Nazis.
Although humanitarian reasons are often one of the pretenses for war often conveyed to us in order to manufacture consent, they are almost never among the primary reasons for invasions. In fact, I would even go so far as to say that your comment, though well intended, is very, very far from the reality of what happened in WWII.
