>>OK without googling I thought it was us because we didn't receive an undertaking from the Germans to withdraw from Poland.
Why did Poland matter to the UK, expect by prestige/treaty? It was way in the East between Germany and the Soviet Union. Look at the mess that led to WWI as well.
Seriously, times were different and IMHO we need to take the lessons and try to do better. My concern would be that if unilateral military action is a pretext for later disproportionate retaliation, then agitators today can find plenty of grievances to justify their own bad behavior. IMHO we need to stomp on that idea and insist that every action's ethics stands alone because two wrongs do not make a right.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1
