The Left was Anti-War even during the lead up to WW2 (and the Right was not)

At Least in the English speaking world.  Also for the purpose of this post I am defining the Center as FDR and those mostly in agreement with him (both Democrats and Republicans) and thus principally the Left are those noticeably to the Left of FDR and the Right those significantly to his Right.

Emma Goldman, the standard-bearer of Anarchism in the United States during the first decades of the 20th Century (who was also Jewish and often a target of Judea-Bolshevik conspiracy theorists) said that while she despised both Hitler and Stalin she would not support a War again either.  The same goes for Paul Goodman.  Another Anarchist who's Anti-Fascist credentials are unquestionable is Dorothy Day, she continued to stand by her Pacifist principals even after Pearl Harbor.

W. E. B. Du Bois, the leading Left Wing Black Civil Rights leader from the end of the 19th Century until the rise of MLK was also very vocal about opposing U.S. involvement in WW2.

The only person in either house of Congress who refused to vote in favor of the Declaration of War following Pearl Harbor was Jeannette Rankin, she was also a vital leader of the Suffragette movement being the first Woman elected to Congress ever.  And at this time she had recently regained her seat specifically to remove an actual Nazi sympathizer Jacob Thorkelson.

Another Left Wing Anti-Interventionist in Congress was Robert m. La Follette Jr who was carrying on the mantle of his father who was one of the most Progressive U.S. Senators of all time.  He was the Congressman removed from his seat by Joseph McCarthy who explicitly used Follette’s Pacifism against him the same way war loving Republicans do today.  Another Wisconsin Progressive enemy of McCarthy who was Anti-War was Alexander Wiley who voted for vital Civil Rights Legislation.  McCarthy himself had more actual Nazi sympathies then these Pacifists, his War time service was in the Pacific and he actually went out on a limb to defend defend Nazi Soldiers in the Malmedy scandal.

Burton K. Wheeler a Northern Democrat who was La Follette Sr.'s Vice Presidential Candidate was the leader of the Non Interventionist Wing of the Democratic Party while also being an ardent New Deal supporter.  Accusations of Anti-Semitism were made against him but they were unfounded.  Another Northern Democrat Anti-Interventionist was David I. Walsh who was one of the very few Senators to vote against the Immigration Act of 1924, the most Anti-Nazi thing you could do in 1924.  Vic Marcantonio is also worth mentioning as is Louis Ludlow, both were leading Progressive Anti-Interventionists who also voted for the 1937 Anti-Lynching Bill.

Rearmament opposition in Brittan from 1933-1935 was primarily led by the Labor and Liberal Parties.  Conservatives like Stanley Baldwin always wanted Rearmament but were quite about it only because it was unpopular.  George Lansbury stood by his Pacifism even as it started to become unpopular within the Labor Party.

But I haven’t mentioned any Marxists yet and that’s where this shall get a bit complicated.

From the aftermath of the Russian Revolution through most of The Cold War generally speaking political Parties with Communist in the name were either taking their marching orders from Moscow or at least considered themselves some other type of Bolshevik/Leninist (like Trotskyist or Right Opposition).  While parties with Socialist in the name were usually not Leninist but absolutely were still Marxists (except the SPD in Germany which was always more Lasallian), they were the Mensheviks, the Luxemburgists, Kautskyists or Bernsteinists of their countries.  Internally everyone in these parties understood they support both of those words, but for branding purposes you only lead with "I’m a Communist” if you wanted to be seen as a Bolshevik.

So Communist Parties were incapable of having ideologically pure positions on Foreign Policy, their position on what their countries Foreign Policy towards Nazi Germany should be changed every time Nazi Germany’s relationship with the U.S.S.R. changed, even Foster and Browder in-spite of their many disagreements still agreed on following Stalin's line on Foreign Policy.  As far as the central claim of the title of this post goes which really refers to different time periods depending on the country, their most Anti-War period was after the War started in Europe but before it had for the U.S.  In fact the only U.S. Presidential Election where this was even kind of a divisive issue was 1940 during this period.  

The American Trotskyists were pretty consistent actually, James P. Canon's SWP and the Shachtmanites and the Revolutionary Workers League all opposed the War.  It was the American Right Opposition (Lovestoneites) that had a schism over it with Jay Lovestone and Louis C. Fraina being the only American Socialists in 1940 who supported intervention while Bertram Wolfe broke with them to oppose Intervention.  Both of them soon stopped being Communists altogether.

Non Bolshevik Marxists like the Socialist Party of Great Britain and the Socialist Party of Canada and the World Socialist Party of the United States were each consistently Anti-War, up to a certain point on the timeline at least.  Meanwhile the Socialist Party of America under the leadership of Norman Thomas was Anti-War up until Pearl Harbor and some members still were even after, this Party was always more popular then the CPUSA.

And here’s the thing, both Left Wing Pacifists like Norman Thomas and Conservative Pacifists like Robert Taft were among the few actually calling out and condemning the Internment of Japanese citizens at the time.  Those who modern pundits keep ignorantly condemning for their lack of enthusiasm to oppose Racist Tyranny overseas were the ones actually standing up to Racist Tyranny at home. 

Likewise Republican Isolationists like Robert Taft and Hamilton Fish were still among the leading advocates in Congress for Anti-Lynching Legislation.  While it was Anti-Isolationist Conservatives like Republican James Wolcott Wadsworth Jr..and the Southern Democrats led by Harry F. Bird, James F. Byrnes and Tom Connally who were the ones opposing Anti-Lynching legislation on “States Rights” grounds.  

Yes you heard that right, most of those notorious Openly Racist Southern Democrats actually supported Roosevelt's Foreign Policy, John E. Rankin went further being one of the few Southern Democrats interested in Anti-Asian Racism he was enthusiastic to go to war with Japan and wanted even more Japanese Americans rounded up into camps, and he was also Anti-Semitic.  Hugo Black was a known KKK member who also supported the War while opposing Anti-Lynching Legislation.  FDR's friend Joseph Daniels was actually among the Red Shirts who did Fascism before anyone in Europe did in 1898. There were a few rare exceptions, Robert Rice Reynolds was the only Southern Senator to vote against Lend-Lease and only he and John Overton voted agaisnt repealing the Arms Embargo.

Theodore G, Bilbo and Ellison D. Smith are Southern Democratic Senators whoa re referred to as obstructed the War effort even though they voted for Lend-Lease, so they're difficult to classify.  But that's it for Southern Democrats who can be even arguably classified as Anti-War.

The Enemy being undeniably Evil is not an excuse to be a War Monger, it wasn’t for Saddam and it shouldn’t have been for Adolf.  The Holocaust could have been avoided peacefully if all the Allied countries had welcomed Jewish Refugees like Norman Thomas wanted them to.

Obviously there were people who opposed the War because they liked Hitler, they were a larger percentage of the Anti-War movement in Britain then they were in the U.S.  But I’m less concerned about weirdos with a fetish for a foreign dictator than I am the more homegrown American versions of what Nazism and Fascism are.  

War tends to be good for Fascism even War against foreign Fascists because at its core Fascism is the cult of Heroism and placing your national pride in your military prowess.  Douglas McArthur and George Patton were American WW2 Generals who it’s not even controversial anymore to say had Fascist tendencies themselves (it is still a bit more controversial to acknowledge the Fascist tendencies of Charles DeGaulle).  And then some younger WW2 veterans went on to found post War American Neo-Nazism, George Lincoln Rockwell, Eustace Mullins and Bryant Bowles, lots of WW2 vets were in the 3rd and 4th Klans, and Strom Thurman was a WW2 vet as well.

Fascinatingly at this time American Nazi Sympathizers couldn't help but continue to express their hatred for Pacifism as a concept even while American Pacifists had the same short term goal.  Elizabeth Dilling who was tried under the Smith Act for her Nazi collaborating in her book The Red Network referred to "Radical Pacifists" as being part of the Communist Conspiracy.

At the very least Leftists who believe it was right to go to War with Hitler should stop using the "Appeasement" as a derogatory term narrative.  That originated with Conservative opponents of Appeasement not The Left but it got adopted by the Left later when we naively decided anything that's "Anti-Fascist" must also be Leftist.  It comes from the inherently Right Wing impulse to equate not wanting War with Cowardice.  That Churchill was a Conservative isn't exactly ignored by Liberals when they lionize his opposition to Appeasement, but they do try to make it sound like he was alone within the Conservative Party, the truth is not even every Conservative named Chamberlain supported Appeasement.  These are the kinds of British Conservatives who if they'd been around during the American Revolution would have called people wanting to concede anything to the Colonists Appeasers, and today they'd call it Appeasement to end the Embargo on Cuba.  Opposition to the Munich Agreement should be framed in terms of how it wronged Czechoslovakia not how it "appeased" anyone.  These British Conservatives were not motivated by the moral outrage at Hitler that makes us view that conflict in Black and White terms however much they may have paid lip service to some of them, what they truly cared about was a fear that letting Germany get away with violating the Treaty of Versailles would make Britain look weak even though some disagreed with it's harsh terms back when it was being debated.

While I mentioned some British Socialists above it is chiefly in the context of the U.S. that I hold the Pacifist position to have been correct, things are different for those on the same continent as the villains in question.  But even then I'm not gonna demonize the principled Left Wing Pacifists, I will always trust those who fought for Peace in the rare circumstances where that was the wrong choice over those who's natural instinct is go along with whatever War the ruling class is currently selling.

Lots of factors were working agaisnt Nazi Germany no single one is enough to remove to make them win not even the U.S.'s involvement.  So it wasn't worth how it actually helped homegrown Nazism and enabled the CIA to recruit experienced Nazis, and build the Gehlen Organization.  The truth is it's precisely because the U.S. entered the War that in the long term the Nazis won.

And Japan's crimes were no worse then Western Colonial Powers, so I'm not at all convinced they were the greater evil in Asia when you look at how opposing them made us allies with Chiang Kai-shek, his ideology actually had more in common with Fascism and Nazism then what the Japanese were doing.  Indeed if it weren't for a change in policy towards the Communists in 1937 that happened largely against Chiang Kai-shek's will the Nazis would have kept supporting him over the Japanese.  The Capitalist Military Industrial Complex had been wanting a War between the U.S. and Japan over the Pacific since before WWI.