In its earliest stages, the "final solution" rose from a searing hatred of the Jewish people in the mind of Adolf Hitler. Anti-semitism was no new phenomenon, and Jew-burning was a common sport in the Germanic middle ages. In those days, the Jews had been suspected of poisoning wells and, later, of murdering Christian children. Those these specific charges were not much heard in the 20th century, popular stereotype of the working classes held the Jew to run the combines and banks, while the ruling classes suspected Jews of manufacturing socialism. William Shirer quotes members of Hitler’s company in WWI who recall Hitler declaring in 1918 that victory was impossible because the "invisible enemies" of the German people would prevent it. These "enemies," the Bolsheviks and Jews, bore the brunt of the Nazi attack once Hitler assumed power in Germany.
Hitler's tirades against the Jews never ceased, from 1918 until his death in 1945, Hitler blamed the Jews for the failings of German society. Though no conclusive evidence exists of a specific occasion on which Hitler learned of the death camps which had been set up in the Nazi puppet Poland, the program neatly fit his expressed goals. Himmler, Goering and the other Nazi leaders vied for Hitler's affections, and it is impossible to believe that they did not keep him well informed of the extermination process.
Systematic persecution began in earnest in 1933, when the SA arranged boycotts of Jewish stores and began to formalize the ghettoization process, discouraging commerce between Jews and Germans. In 1935 the Nuremberg laws were passed, establishing racial definitions and preventing marriage between Jews and Germans. Jobs and legal protection came to depend on the Nuremberg gradations as well. In 1938, Hitler felt ready to lead the people in a massive uprising against the Jews, resulting in Kristallnacht, in which Jewish shops were destroyed, bookstores burned, and the few remaining synagogues were destroyed. Popular support for this was mixed, and the insurance costs on the destroyed buildings were substantial. The same year, Jews were banned from holding civil service jobs, their citizenship was revoked and they were banned from most professional positions, including jobs in law and medicine. Hitler was growing impatient with the possibility of spawning a mass revolt against the Jews, and his rhetoric and policies turned more towards secret slaughter.
From 1939 until 1941, the Germans shipped huge numbers of Jews from newly conquered territory into Poland's Gouvernement General. This solved the immediate problem of getting them out of Hitler's sight, but presented a long-term problem in terms of living space and food. The Germans might well have left most of them there to starve, except that the opening of the eastern front in 1941 made the situation more complicated. Leaving the Jews in Russia made no sense, and shipping them to Poland would have brought them closer to Germany. Given that most could be presumed to be Marxists anyway (in Nazi logic), the most efficient program would be to kill them. The Einsatzgruppen were established for this purpose and killed hundreds of thousands of Jews as the German armies swept eastward.
Next, the Nazi deported Jews from Germany itself, starting in November 1941. They were murdered. Clearly, a new pattern had been established: the collection of civilians from one area, to be deported and killed elsewhere. The transition from this to the final mass-killing of Auschwitz, Bergen-Belsen and the like was a minor one.
In January 1942, senior Nazi officials, senior servants and the like met in Berlin at the Wannsee Conference and decided that a new bureaucracy was needed to oversee the slaughter of the Jews. The army felt that it hurt moral to keep the Einsatzgruppen occupied in this way. Besides, if the program could be kept secret, the odds of public backlash would be minimized.
Soon after, death camps were constructed throughout Poland. From the middle of 1942 through the end of the war three years later, these camps operated in supposed secrecy, killing hundreds of thousands of Jews, Gypsies, Marxists, homosexuals and cripples, each month.
Hitler would have had great difficulty with so comprehensive a program, had it not been for the war. He certainly could have found individuals willing to do the killing, but he likely would have had trouble collecting the Jews in territory he did not directly control. In those areas which resisted Nazi demands, Jews were, by and large, safe. The King of Denmark declared that, if the Nazis wanted to kill the Jews, they would have to kill him first; the Nazis backed off. Given adequate secrecy, he might have been able to kill most of the Jews in Germany, something near 150,000 individuals. Though the French and Poles had reputations for anti-Semitism, their hatred of the Germans probably exceeded their distrust of the Jews, and I can not imagine their turning their Jews over to the SS.
Every German bears some responsibility for allowing the deportations, though most probably had little idea of the killings and can therefore be absolved of guilt for those deaths. Those who knew what really happened in the concentration camps are doubly guilty: for not intervening (a difficult prospect) and for not spreading the word (a much easier prospect).
from my homework for Historical Studies B-54 on November 24, 1991.