The following quote is from a news article which you can read in full here.
Two escapees from Auschwitz, Rudolf Vrba and Alfred Wetzler, fully aware of the horrid purpose of Auschwitz, memorized as best they could the physical details of the entire Auschwitz-Birkenau death camp and reported it to the Slovak underground in April of 1944. For a variety of reasons not attributable to any agency of the United States, their report did not reach the War Refugee Board in Washington, the United States agency with the responsibility of saving Jewish lives, until June 24 and the British Foreign Office until July 4. By then, over half of Hungarian Jewry had already been sent to Auschwitz and almost all of them murdered.
I have written several blog posts about Rudolf Vrba and Rudolf Vrba: https://furtherglory.wordpress.com/tag/rudolf-vrba/
The following information is from my scrapbookpages.com website:
The plight of the Hungarian Jews first came to the attention of the world when, on April 7, 1944, two Jewish prisoners, Rudolf Vrba, aka Walter Rosenberg, and Alfred Wetzler, managed to escape from Birkenau, the infamous Auschwitz II camp where the gas chambers were located. They made their way back to Slovakia, where Vrba’s mother was still living, and wrote a report which soon reached the hands of the Pope, the King of Sweden, and even President Franklin D. Roosevelt.
The Hungarian government and Admiral Horthy were informed that Vrba and Wetzler had proof that the Jews were being gassed at Auschwitz. Vrba, who worked at the Judenrampe, the train platform where the Jews disembarked before the railroad line was extended, had counted the number of Jews who arrived at Birkenau and were then never seen again. Vrba’s estimate was that 1,765,000 Jews had been gassed at Auschwitz-Birkenau by March 1944, just before he made his escape.
The current estimate of the number of Jews deaths, from all causes, at Auschwitz-Birkenau is 1.1 million. Why was Vrba’s estimate so wrong?
Two other prisoners, Arnost Rosin and Czeslaw Mordowicz, also escaped from Auschwitz at the end of May and wrote a report which told about the beginning of the “Hungarian Action” and the mass murder of the Jews.
Secretary of the Treasury Henry Morgenthau, Jr. and Judge Samuel I. Rosenman, two Jewish advisors to President Roosevelt, urged him to intervene, according to Robert E. Conot, who wrote “Judgment at Nuremberg.” Roosevelt threatened that “Hungary’s fate will not be like any other civilized nation’s…unless the deportations are stopped.” With a population of 125 million people in America in 1933, when the Nazis first came to power, the USA had plenty of room to absorb all of the approximately 15.6 million Jews in the world, but the American Congress would not change the laws that limited Jewish immigrants until 1948.
On July 2, American planes bombed Budapest and its railroad facilities in an attempt to stop the deportation of the Hungarian Jews, according to Conot. The King of Sweden and the Pope also intervened and put pressure on Horthy to stop the deportation. The bombing of Auschwitz was briefly considered, but was rejected.
On October 8, 1944, Hungary formally sought peace terms with the Allies, according to the book entitled “The Last Days,” which was published in conjunction with a documentary by the same name, filmed by Steven Spielberg. Hitler had anticipated this move, and the SS protected the pro-Nazi Hungarian leaders of the Arrow Cross fascist political party from arrest while Otto Skorzeny, the famous German commando, and his elite unit kidnapped Horthy’s son. Horthy’s coup was stopped and the Germans forced Horthy to appoint Ferenc Szalasi of the fascist Arrow Cross party as the prime minister of Hungary.
Adolf Eichmann then returned to Hungary and began negotiations with the Hungarian government to deport 50,000 Hungarian Jews to Germany to work in building anti-tank barriers and in the munitions factories in the concentration camps. Due to the destruction of the railways by Allied bombing, the Jews were forced to march on foot to the border between Austria and Hungary where they were then put on trains and taken to various concentration camps, including Mauthausen, Gunskirchen and Buchenwald. Hungarian women were also sent on the march and eventually reached the main Dachau camp, where they were then sent to one of the Dachau sub-camps.
One of the 7,000 Budapest Jews, who were sent to Auschwitz in 1944 and then transferred to Buchenwald or other camps, was the famous Hungarian novelist and winner of the Nobel Prize for Literature in 2002, Imre Kertész . In several novels, Kertész wrote about the Holocaust, although not about his personal experience.