Band on Run, there are several issues with thinking that Holocaust and concentration camps could be stopped. They were in existence since late 1930's and Germany was not in war until 1939 and USA/USSR until 1941. In my hometown Jews were already killed in April 1939 a onward nd first transports occurred from Ostrava around March 1939. Until 1942 Germans were a master of Europe. Whatever they decided to do, it could not be stopped by anyone. There was no stronger power until their defeat at the Stalingrad. German economy in 1940 was even larger than USA due incorporation of Austria and Protectorate of Bohemia and Moravia. No country in Europe before WWII would start a war on behalf of oppressed minorities. This was status established by Peace of Westphalia in 1648 which forbade European states in interfering in other countries affaris on behalf of the national or religious minorities. This status was prerserved for the next 300 years.
When Germany occupied most of Europe, the biggest genocides happened in Eastern Europe. Nazi regime very quickly carried extermination with their facilities. Until 1943 the area was out of reach for RAF and USAF from their bases in UK. There was no way that successful air raides could be carried that far into the Eastern Europe. That was also reason why most of the Eastern Germany, Protectorate, Slovakia, and Hungary, Vienna have not seen bombing until much later part of the WWII (Prague, Vienna, Budapest, Bratislava were not bombed until 1944). Most of the raids on Central and Eastern Europe were carried from Italian bases once British and American occupies southern tip of Italian penninsula. It would be impossible to stop the holocaust before 1943 from air raids alone. Additionally, Central Europe had dense railway grid with 100,000 miles of tracks that interconnected and not even a collapse of air defenses in Germany could knock them out. In March 1945 the tracts and rails worked so well that it carried 1 million troops in that month alone and many more refugees. Destruction of such vast network was almost not possible from the air campaign even with systemathic targetting as USAF started in summer of 1944. Dresden rail junction functioned two days after air raides. The camp facilities also held thousands of POW and forced laborers, so bombing of them would kill thousands of other people.
Did people knew what was happening? Yes they knew, but they were not aware of the extent of the killing. It was not imaginable for the society the horror until the war was over. And majority of population did not really cared at that time. People attempted to survive. They are happy that are not that one on the end of the rope. Survivors do not care about the victims. The same mentality existed in French Revolution during the Reign of Terror. Thousands of people were guillotined and the victims were immediatelly forgotten the day they lost their heads. When anyone later inquired what French did in 1794 the simple answer was "I do not know, I just tried to survive". Executions were often carried in public and announced on press, radio and filmed. Brno' mass shooting range was opened to public. Mass executions also happened in the city center as entertainment for Nazis like mentioned here in downtown of Prague during Xmas 1941: http://www.youtube.com/watch?v=tM902N7UIjY. Destruction of Lidice, its leveling, and killing all men was filmed, announced, and used in cinema before start up movies as way to inflict fear into the population. When you see newspaper from occupied Europe, you see the list of people who were executed daily. With their name, age, address, and profession.
Many JWs in the 1930's started their own fate with a collision with the government. In Czechoslovakia which was democracy until 1938, the JW on purpose violated publishing laws and played a martyr for their faith. Government did not want foreigners distributing literature in time were war was expected. And there was issue with amount of publication than anyone could distribute while not violating tax and publishing laws. JWs could not often explain what they weer doing with bag of books and where the money went after they sold it out. Situation in Germany after 1933 was much worse and they would have to expect violent suppresion at the hand of the totalitarian regime.
