As Soviet armies advanced in 1944 and early 1945, Auschwitz was gradually abandoned. On January 18, 1945, some 60,000 prisoners were marched to Wodzisław Śląski, where they were put on freight trains (many in open cars) and sent westward to concentration camps away from the front. One in four died en route from starvation, cold, exhaustion, and despair. Many were shot along the way in what became known as the “death marches.” The 7,650 sick or starving prisoners who remained were found by arriving Soviet troops on January 27, 1945.

During the Battle of France in 1940, De Gaulle's 4th Armour Division and elements of the British 1st Army Tank Brigade in the British Expeditionary Force both made probing attacks on the German flank, actually pushing into the rear of the advancing armored columns at times (See Battle of Arras (1940) ). This may have been a reason for Hitler to call a halt to the German advance. Those attacks combined with Maxime Weygand's Hedgehog tactic would become the major basis for responding to blitzkrieg attacks in the future: deployment in depth, permitting enemy forces to bypass defensive concentrations, reliance on anti-tank guns, strong force employment on the flanks of the enemy attack, followed by counter-attacks at the base to destroy the enemy advance in detail. Holding the flanks or 'shoulders' of a penetration was essential to channeling the enemy attack, and artillery, properly employed at the shoulders, could take a heavy toll of attackers. While Allied forces in 1940 lacked the experience to successfully develop these strategies, resulting in France's capitulation with heavy losses, they characterized later Allied operations. For example, at the Battle of Kursk the Red Army employed a combination of defense in great depth, extensive minefields, and tenacious defense of breakthrough shoulders. In this way they depleted German combat power even as German forces advanced. In August 1944 at Mortain, stout defense and counterattacks by the US and Canadian armies closed the Falaise Gap. In the Ardennes, a combination of hedgehog defense at Bastogne, St Vith and other locations, and a counterattack by the US 3rd Army were employed.

Though the Nazis tried to keep operation of camps secret, the scale of the killing made this virtually impossible. Eyewitnesses brought reports of Nazi atrocities in Poland to the Allied governments, who were harshly criticized after the war for their failure to respond, or to publicize news of the mass slaughter. This lack of action was likely mostly due to the Allied focus on winning the war at hand, but was also a result of the general incomprehension with which news of the Holocaust was met and the denial and disbelief that such atrocities could be occurring on such a scale.
Jewish deportees arriving at Auschwitz-Birkenau immediately underwent selection. The SS staff chose some of the able-bodied for forced labor and sent the rest directly to the gas chambers, which were disguised as shower installations to mislead the victims. The belongings of all deportees were confiscated and sorted in the "Kanada" (Canada) warehouse for shipment back to Germany. Canada symbolized wealth to the prisoners.
One element that was lacking from the German army in 1914 was the ability to move long distances quickly. Had the German army been mechanised at the outbreak of World War One, it is likely that the outcome of the war would have been very different. As things were then, the German army was unable to defeat its enemies decisively in the war's early battles, and reluctantly settled into trench warfare in late 1914.

Some prisoners kept diaries, recording life inside the camp, so that the world would one day know the story of what happened to them. Others collected evidence of the killings and events within the camp, burying it in the hope that one day someone would find the evidence of the atrocities. Prisoners had to be careful to make sure these form of indirect resistance went undiscovered by the SS guards and kapos.

When Germany invaded Poland in September 1939, it gained control of about 2 million Jews in the occupied territory. The rest of Poland was occupied by the Soviet Union, which had control of the rest of Poland's pre-war population of 3.3–3.5 million Jews.[141] German plans for Poland included expelling gentile Poles from large areas, confining Jews, and settling Germans on the emptied lands.[142] The Germans initiated a policy of sending Jews from all territories they had recently annexed (Austria, Czechoslovakia, and western Poland) to the central section of Poland, which they called the General Government. There, the Jews were concentrated in ghettos in major cities,[143] chosen for their railway lines to facilitate later deportation.[144] Food supplies were restricted, public hygiene was difficult, and the inhabitants were often subjected to forced labor.[145] In the work camps and ghettos, at least half a million Jews died of starvation, disease, and poor living conditions.[146] Jeremy Black writes that the ghettos were not intended, in 1939, as a step towards the extermination of the Jews. Instead, they were viewed as part of a policy of creating a territorial reservation to contain them.[147][l]
Sprawozdanie 6/42 was sent to Polish officials in London by courier and had reached them by 12 November 1942, when it was translated into English and added to another report, "Report on Conditions in Poland". Dated 27 November, this was forwarded to the Polish Embassy in the United States.[341] On 10 December 1942, the Polish Foreign Affairs Minister, Edward Raczyński, addressed the fledgling United Nations on the killings; the address was distributed with the title The Mass Extermination of Jews in German Occupied Poland. He told them about the use of poison gas; about Treblinka, Bełżec and Sobibor; that the Polish underground had referred to them as extermination camps; and that tens of thousands of Jews had been killed in Bełżec in March and April 1942.[342] One in three Jews in Poland were already dead, he estimated, from a population of 3,130,000.[343] Raczyński's address was covered by the New York Times and The Times of London. Winston Churchill received it, and Anthony Eden presented it to the British cabinet. On 17 December 1942, 11 Allies issued the Joint Declaration by Members of the United Nations condemning the "bestial policy of cold-blooded extermination".[344][345]

December 11, 1941 - Hitler declares war on the United States. President Roosevelt then asks Congress for a declaration of war on Germany saying, "Never before has there been a greater challenge to life, liberty and civilization." The U.S.A. then enters the war in Europe and will concentrate nearly 90 percent of its military resources to defeat Hitler.

Irena Adamowicz Gino Bartali Archbishop Damaskinos Odoardo Focherini Francis Foley Helen of Greece and Denmark Princess Alice of Battenberg Marianne Golz Jane Haining Feng-Shan Ho Wilm Hosenfeld Constantin Karadja Jan Karski Valdemar Langlet Carl Lutz Aristides de Sousa Mendes Tadeusz Pankiewicz Giorgio Perlasca Marion Pritchard Ángel Sanz Briz Oskar Schindler Anton Schmid Irena Sendler Klymentiy Sheptytsky Ona Šimaitė Henryk Sławik Tina Strobos Chiune Sugihara Casper ten Boom Corrie ten Boom Johan van Hulst Raimondo Viale Raoul Wallenberg Johan Hendrik Weidner Rudolf Weigl Jan Zwartendijk