When did the allies find out about the killing of Jews during WW2

What was known 100%, was not remotely attempted to be kept secret, was the treatment of German Jews in Germany -- that they were robbed of businesses, professions and property and strongly encouraged to immigrate was completely clear. One might argue that this was not genocide but you have to ask what is the ultimate intention of a policy that first impoverishes a group -- that is to say, makes it impossible for them to live? Did the Germans intend really to allow the Jews to establish a separate nation which would then be allowed to prosper or at least pursue an independent existence? I think it is clear that genocide was the final result even if that was not planned at firt.

Can't give you a lot of specifics, but I recall being taught at school (in Poland) that the Polish intelligence learned of this almost immediately, but the Allied forces didn't believe the reports for quite some time.

There's also the published works of Victor Gollancz, about whom the Wikipedia page says (here):

Gollancz publicised the anti-Semitism of the Nazi regime early on; in 1933 he had published the compilation volume The Little Brown Book of the Hitler Terror and Fritz Seidler's book on the Nazi persecution of the Jews The Bloodless Pogrom in 1934. In the summer of 1942 Gollancz came to realise that he and the rest of the world had been seriously underestimating the horrific extent of the Nazi persecution of the Jews. He explained in his 16,000 word pamphlet Let My People Go, written over Christmas 1942, that between one and two million Jews had already been murdered in Nazi controlled Europe and "unless something effective is done, within a very few months these six million Jews will all be dead."

The pamphlet "Let My People Go" (mentioned above) was published in January 1943. A photo of it was recently shown on a tweet and is included below.

Here's a personal story from my German grandparents.

I don't know what year this happened, but my (now deceased) Opa would have turned 18 in early '41, if the German Army used that age or not?

He was ethnic German, but he had grown up since birth on a farm in Yugoslavia, as Germans had done a lot of emigration and settling in the generation or two before. I don't know in what order things happened, but in the first half of WW2, there was anti-German sentiment in Yugoslavia, ethnic Germans were called back to Germany to join the war effort, and Germany occupied Yugoslavia.

He was identified as being smart and capable, and was told he was going to be drafted into the SS. My Oma says their community wasn't exactly aware of the concentration camps and mass killings, because most of the news they got was propaganda. But there was knowledge of escalating government-backed hate against Jews, and a general feeling and quiet discussion about rumours that even worse things that were hard to believe were being done or planned. And that the SS was the group that ran the brutal side of things.

Opting out of the military probably wasn't an option, and who knows, he might have still wanted to support his nation in the war effort, while not wanting anything to do with killing citizens. So he decided to quickly volunteer to be a paratrooper, and once he was enlisted there, he was shipped out and couldn't be drafted into the SS.

I recall hearing he saw the most wartime action down in Italy, skydiving down to targeted locations to blow up bridges as Germany retreated, with the goal of slowing down the Allies who were advancing Northward.

My Oma said that after the war, the reality of what had been done by the SS was way more than any common people had imagined.

In my opinion it's good to discuss this kind of thing, even if painful, because most people in the world would be so shocked and horrified about it, that they would be inclined to do their part to make sure it doesn't happen again, even if a government and a racist movement start to gain power and influence.

Many Americans considered reports of Nazi atrocities "fake news" right up to the time the Camps were liberated. Anti-semitism along with racism, extreme nationalism and isolationism was the norm for much of America in the period between the wars.

Americans in the early 1940's probably didn't care one way or the other about the fate of Europeans Jew's, just make damn sure they don't try to immigrate to America. Reference the story of the SS St.Louis.

Sad to say the situation with Non-Christian refugees today is pretty similar.

That Jews were being grossly mistreated and in some cases killed was known since the early 1930s and indeed there were attacks on Jewish people and businesses by the SA as far back as 1920, before the Nazis came into power. This of course pales in comparison to the organised mass-killings of the Holocaust, but that Jewish people were being actively persecuted was known from before the war.

gets emotional when he discovers a Hitler Youth knife, I could only assume it was suggested that he knew about the killing of Jews.

That also doesn't completely follow. That children were being indoctrinated in a youth organisation that had such items among its paraphernalia is horrendous enough even if one only knew about the degree of persecution that was public knowledge in the early days of the Reich, and not the organised genocide.

Another person I feel deserves to be mentioned is Polish soldier Witold Pilecki. He deliberately got himself arrested in september 1940 and was send to Auschwitz.

While there he organized a resistance group and provided invaluable details to the Polish resistance, including the number of inmates arriving and dying. These reports were being forwarded to London from March 1941 forward. In April 43 he decided to escape Auschwitz and succeeded.

He was executed for treason on 25th of May 1948 under Soviet rule.

Source: https://en.wikipedia.org/wiki/Witold_Pilecki

It is possible to know things in many different ways.

One can known things without totally knowing them - as many people fail to make use of what they learned in school while making decisions later in life. It is possible to believe things without totally believing them - as many people go through life partially believing what they deduced about the world as little children and partially believing what they learned about science in school, without making any effort to resolve any contradictions.

Thus many allied citizens may have partially believed what they heard about Nazi atrocities against Jews and others. They may have believed enough to support being tough with the Germans and committing war crimes against them because they were evil Nazies, but not enough to overcome their own prejudices against Jews or to advocate helping Jews by permitting more Jewish refugees to enter their country or to advocate changing allied strategy to stop the Holocaust as soon as possible.

Thus many allied citizens may have believed in Nazi atrocities against the Jews enough to support total war against Germany while still disbelieving in them enough to be surprised and shocked by the discovery of the death camps at the end of the war in Europe.

I try not to post things on HSE without evidence, but history is funny. If we disregard the personal accounts then were missing such a large part of history. So for that reason, I relate to you what I was told by My great grandfather who server in Europe during WWII.

He's dead now, but I asked him when I was in just out of high school and was thinking about joining one branch of service or another, because of 9/11 and the war in Iraq. I only mention that so you have context. Remember these "facts" come from a conversation, and I can't prove any of them. Also keep in mind that the quotes are as I remember them. SO they could be a bit off.

So the first thing to remember is that the internet and even T.V. didn't exist like it does today. He got most of his news from the radio and newspaper. He lived in a rural area on a farm, so the news paper was only on weekends.

He described the events leading up to the US entry in to the war (this is a US perspective) as kind of meh. His words were "it was somewhere else, and didn't effect him, or his family." There were stories of how the alies were doing and how bad some countries had it. There was a general "cheering" for the alies. But in his world, as he put it, "if it didn't involve the chickens or the pigs I had better things to do".

Then stories started coming out about how jews were treated. Some of them he didn't believe, some were kinda of so what? Jews were being mis-treated and that was generally believed, though no one really know the extent, some of the reports sounded like propaganda. He reminded me that even then there was a strong anti-war feeling. Pro-war was gaining support, but mostly we (the US) wanted to stay out of it. We had our own issues.

He kinda explained it like, he knew Jews were being killed for being jews, but it's not like the US was some beacon for equal rights. We had our own racial problems and how were US soldiers going over there and killing others supposed to be better then them killing "their own". Remember before WWII the US was not the "police force" we are today. (btw he always supported the police actions from NATO, because the inaction before our entry into WWII, he felt, let the evil go on, and lessons learned)

So mostly, yes he knew Jews were being killed, just for being Jews, but felt that sending US troops, would make it worse not better. Specially as in the US, killing black people for being black was a thing, and we had our own issues to work on.

Then Pearl Harbor. I'll skip over that part.

He enlisted, and went to the European front. He explained it as cold, wet, and missirable. Lots of waiting, then a few moments of action, followed by lots more waiting. But he didn't want to talk about the fighting.

He said that the military news couldn't be trusted, and was mostly thought of as a joke. It started telling stories about "camps" but, no one really believed them. Just war time propaganda. And at the time he had more pressing matters like staying warm. He really talked about how the main war for him was the cold and hunger and not the Germans or the Jews. Just a struggle to stay warm and eat.

But as the war started to die down, and things "relaxed" a bit, more stores started to come out, from other soldiers, from letters from home. That's how learned about concentration camps. Even then he still didn't believe it. Not really. He thought they were exaggerating. But then his group was assigned to help with transporting some prisoners from a "camp". He wouldn't say much on it, except that the news and other soldiers were right. For him it was that experience that led him to believe the stories. Right up to that point, it was a bad thing that happened but no worse then any other social injustice.

He had related it to what he knew. He thought it was like when black people were beaten, killed, hung by mobs etc. Bad, evil even, but part of what the world was going through. Nothing to deploy an army for, something needed to be done but what? He hated how black people were treated, but had no idea how he could fix it. Call the police? he knew better. To him the "Jew stories" were the same. Wrong, but what could he do, call the police? That didn't work here so why should it work there. He really explained it like that. He felt it was bad, but society had to change, and that was a messy process. Once that the US should not get involved in because we had our own messy processes. But after that day, he didn't feel that way. This wasn't a shift in society, or racial tension, it was just evil. Pure and utter evil. And that's all he would say on that.

So for him, and his friends, they knew something was "wrong" but not the extent. Remember the US had "interment camps". So a camp full of Jews wasn't, by it's self, all "that" bad. It wasn't till the end of the war that the full extent of what was happening sunk in.

@sempaiscuba answered the question as asked, I only have a note:

While, indeed, the Nazi atrocities (including mass murder of Jews) were well known to everyone who wanted to know, the Allies made no effort to spread the information because they did not want the war to be perceived by their citizens as a "Jewish war", as Hitler tried to position it. E.g., Jews are not mentioned in the Statement On Atrocities (Moscow, 1943) - although many others are, e.g., Cretan peasants.

PS1. Of course, I am not implying that the Allies should have publicized the Nazi slaughter more. It certainly would have hurt their war effort.

PS2. Another data point (pointing in the opposite direction) is Posen speeches: in October 1943 the Nazi leadership believed that "SS officers, ... Reichsleiters and Gauleiters, as well as other government representatives" might be able to claim being unaware of the Final Solution.

The first eyewitness to contact western leaders about situation of Jews in occupied Europe was Jan Karski. Based on his testimony, Polish Foreign Minister in exile made a note addressed to United Nations called 'The mass extermination of Jews in German occupied Poland'. Karski personally spoke with the British Foreign Secretary Anthony Eden, telling him about the situation in Warsaw he witnessed.

On 28 July 1943 Karski met with President Franklin D. Roosevelt, reporting the situation in Poland. During their meeting Roosevelt asked about the condition of horses in Poland. Roosevelt did not ask one question about the Jews.

Karski had meeting with other members of the government, for example Felix Frankfurter, who was skeptical of Karski's report, said later "I did not say that he was lying, I said that I could not believe him. There is a difference."

Even shortly after the war holocaust was not such a big thing and antisemitism was still wide spread. Some people argue that it has changed only after the jewish community in USA begin to fund historical research on holocaust.

Like this Swedish front page from December 18, 1942 it was known. The headline says "Planer på att utrota judarna förverkligas" (Plans to exterminate the Jews put into action). It speaks of hundreds of thousands of victims. Based on the British Foreign Secretary, Anthony Eden's proclamation.

So it was reported in regular newspapers, but perhaps not the newspapers some people preferred or perhaps they only read the sport section.

I want to offer a personal perspective: I am German. I learned about the Holocaust in school. I visited concentration camps. I have friends who lost family in concentration camps. I watched documentaries and Schindler's List. I read Anne Frank's Diary. I talked to Holocaust survivors. And yet, I feel I haven't fully comprehended the horror, the inhumanity, the absolute and total disregard for life and humanity, the robotic, industrial, mechanized "efficiency" (for want of a better word) of it. It truly is an "unbelievable" (in the literal sense of the word) horror.

I remember well both the scenes you describe. I don't think the soldiers are surprised about the fact that the Nazis murdered Jews. They are shocked about the extent, the efficiently organized, industrial-scale mass murder. Think about it: this wasn't long after Henry Ford. Can you imagine suddenly discovering that there must be a German Henry Ford who took as much pride in figuring out ways to make mass murder cheaper and more efficient as Henry Ford did for building cars? That this scheme must have been devised, designed, optimized, and implemented by highly intelligent people who chose to dedicate their intelligence and their skills to such a horrific endeavour instead of, say, improve the economy, invent cool things, make the world safer for factory workers, or cure diseases?

Imagine growing up during the Golden Age of Industrialization with its utopian visions and then discovering that.

The soldiers might have known everything about the Holocaust. But, as they say, seeing is believing. Knowing about it and seeing it first-hand are two very different things.

Information regarding mass murders of Jews began to reach the Allied leadership soon after the invasion of the Soviet Union in late June 1941. The volume of those reports increased with time. This was some six months before the Wannsee Conference and the formalisation of the Nazi's "Final Solution to the Jewish Problem". I'm not aware that this information was made public at that time.

On 17 December 1942, the British Foreign Secretary, Anthony Eden, issued a proclamation on behalf of the "United Nations", condemning the "extermination" of the Jewish people in Europe and declared that they would punish the perpetrators. From that point, the general public were aware that the Nazis were murdering Jewish populations in the countries that they had invaded, but I don't think anyone really understood the the true horror until the camps were liberated by Allied forces.

Anthony Eden's full statement and the House of Commons debate can be read on Hansard.