I understand this question is going to get generalised answers, but I'm also intrigued why there were no major pacifist movements from a generation who had already suffered a major war in their lifetimes. I'm interested in responses from any country that participated in both wars, but answers regarding the main participants on both sides would be the most interesting please. Thank you!
I'd love to hear from someone here with a wider base of knowledge on this question, but one of the striking observations in Lynne Olson's book Troublesome Young Men is that the "belligerent" clique that formed around Churchill and which opposed appeasement was primarily composed of veterans of the trenches like Anthony Eden, Harold MacMillan, Leo Amery, and Lord Cranborne-- not to mention Churchill himself. Ronald Cartland could be included as well for having lost his father in the Great War, he would also soon become one of the early fatalities of the Second.
This is in contrast to Baldwin, Chamberlain and many of the other "appeasers" who did not serve.
That said, of course, this is hardly a representative sample, and when Chamberlain returned from Munich and declared that he'd achieved "peace for our time" he was met with genuine adulation, which most certainly must have included WWI veterans.
Just a layman recalling the 'so what' of what I've read, but I recall an interesting takeaway from The Price of Glory: Verdun 1916, which described how the French psyche may have been effected by the Great War. Unfathomable loss of life, unmatched physical destruction. The population wasn't willing to bear another struggle like the one they had just barely overcome, and so, surrender was a more presentable option from the start.
There were of course many, particularly veterans who opposed this, yet, consider the heartbreaking story of Marshal Pétain, who gave so much in resisting the Germans, but ultimately was forced to advocate appeasement/surrender in order to protect the people of France.
His trial in the postwar years surely amplifies the voices of those who felt betrayed by his surrender, but the French population largely followed him in 1940, I wonder if, for many, that anger wasn't noise to cover their own shame.
I'd really like to hear from actual experts on this topic too. I wonder, as the end neared for Germany in the second world war, how many veterans of the Kaiser's army would wind up mobilized in Germany's defense. How many would be killed? Might any have called for a cessation of hostilities as the cost grew heavier and the prospects more grim?