In several instances, Jews took matters into their own hands and violently resisted the Nazis. The most notable was the 28-day battle waged inside the Warsaw Ghetto. There, a group of 750 Jews armed with smuggled-in weapons battled over 2000 SS soldiers armed with small tanks, artillery and flame throwers. Upon encountering stiff resistance from the Jews, the Nazis decided to burn down the entire ghetto.
Anne had expressed the desire in the rewritten introduction of her diary for one person that she could call her truest friend, that is, a person to whom she could confide her deepest thoughts and feelings. She observed that she had many "friends" and equally many admirers, but (by her own definition) no true, dear friend with whom she could share her innermost thoughts. She originally thought her girl friend Jacque van Maarsen would be this person, but that was only partially successful. In an early diary passage, she remarks that she is not in love with Helmut "Hello" Silberberg, her suitor at that time, but considered that he might become a true friend. In hiding, she invested much time and effort into her budding romance with Peter van Pels, thinking he might evolve into that one, true friend, but that was eventually a disappointment to her in some ways, also, though she still cared for him very much. Ultimately, it was only to Kitty that she entrusted her innermost thoughts.
Although the composition of the ground, largely sand, was favorable for ground-penetrating radar, the dense forest surrounding the site interfered enough with the radar signals that they decided to try another tack. Paul Bauman and Alastair McClymont, geophysicists with Advisian WorleyParsons, a transnational engineering company, had more luck with electrical resistivity tomography, or ERT, which was originally developed to explore water tables and potential mining sites. ERT technology sends jolts of electrical current into the earth by way of metal electrodes hooked up to a powerful battery and measures the distinctive levels of resistivity of different types of earth; the result is a detailed map to a depth of more than a hundred feet.
The Polish government-in-exile in London learned about the extermination camps from the Polish leadership in Warsaw, who from 1940 "received a continual flow of information about Auschwitz", according to historian Michael Fleming. This was in large measure thanks to Captain Witold Pilecki of the Polish Home Army, who allowed himself to be arrested in Warsaw and spent 945 days in Auschwitz from September 1940 until April 1943, organizing the resistance movement inside the camp.
The ideology of Nazism brought together elements of antisemitism, racial hygiene, and eugenics, and combined them with pan-Germanism and territorial expansionism with the goal of obtaining more Lebensraum (living space) for the Germanic people. Nazi Germany attempted to obtain this new territory by attacking Poland and the Soviet Union, intending to deport or kill the Jews and Slavs living there, who were considered by the Nazis to be inferior to the Aryan master race.