Oh that’s fair, in my last comment I said “invade” which was careless word choice. What GP said and what I was reacting to was “conquer”, as in invade and then continue to occupy after the war concludes.

The France and Britain invasions were pretty straightforwardly defensive actions by Germany. They both allied with Poland and when Poland was invaded (an aggressive act by Germany) they declared war on Germany. What evidence is there to suggest that Germany would still have invaded France if France and Britain had simply abandoned Poland? Note that I’m not asserting that they “should have” abandoned Poland, just that the “we’ve got to stop them before they conquer the whole world” is almost always a bogeyman.

This line of reasoning is even more revealing when you realize how the western allies dropped Poland like a bad habit at the end of the war. The Polish government-in-exile that fought with the western allies never regained control of the territory of Poland -- the current Republic of Poland is not a continuation of the pre-war government or the government-in-exile. One could make the argument that the poles were just a convenient excuse for Britain and France to enter and expand the war.

Are you suggesting that the west should have gone further and declared war on the USSR after Germany's defeat, such that, it is consistent with the view that Poland should exist with its pre-war government, otherwise, the governments of the west are just hypocrites? Was the cold war not hot enough such to meet this bar? These glancing apologies for Germany's actions in WW2 seem ludicrous.

I believe the idea is realistically more that the allies should not have declared victory as they did, if a free Poland was truly their goal.

If you fail to achieve your stated goal and you still declare victory, you are either lying about your goal, or you are lying about your victory.

Invading the USSR probably wasn’t the most efficient way to ensure a free Poland. Have you heard of negotiation? Did the USSR really not want anything that the Allies could give to ensure a free Poland? Or did the Allies simply not value a free Poland enough to give up something big enough? If it was really their main reason for entering the war, don’t you think the negotiations math would have worked out differently?

While that can be an interesting lens (though I think it erases material context), the point I was discussing was not about the validity of someone declaring victory, but rather, about countries invading their neighbors.