how did the Germans know?

-The majority of the jews lived in the city.
-The Dutch had one of the best Citizen Registers at the time. (name, address, religion)

80 per cent was deported to a work camp(40 per cent in Belgium and France) and the jews didn't give any resistance as they didn't know they would later end up in destruction camps such as Sobiborg and Auswitz.

The rest that went into hiding couldn't have gone far from their homes as they needed a passport(which stated religion) to take the train.

So with the occasional razzias no jew was safe.

the nazis also paid money (at least 25 guilders) to collaborators who turned jews in. there were a lot of people in the shop, the robber, etc. who may have been suspicious and learned things.

Farewell,and may the blessing of Elves and Men and all Free Folk go with you.

I think they were betrayed by somebody who told the Natzi's where they were.

One of the first things that the Nazis did, regardless of any history of such acts in the country they took over, was require Jews to register as such.

At this point, no one knew that they would be rounded up and exterminated.

Later, they required all businesses that were owned by Jewish people to divest themselves into non-Jewish ownership.

At this point, no one knew that they would be rounded up and exterminated.

Later, they required all Jewish people to wear markings that identified themselves as being of Jewish descent.

At this point, no one knew that they would be rounded up and exterminated.

Then they started rounding up the Jews.

At this point, no one wanted to know what would happen to them.

Then they offered bounties on Jews in hiding. Strict rationing was in place, and collaboration bought not just money, but also privileges. Items that were impossible to get. Whatever your vice, the Nazi commanders could offer it.

At this point, the people just hoped that they wouldn't be next.

Service equals citizenship. Would you like to know more?

[deleted]

Actually, I don't think it's ever been discovered who actually turned them in but the story I always heard (in school) is that it was likely the burglars that broke in earlier heard them and became suspicious and waited. As the families discovered the burglars and were all crotched in the stairway trying to listen, that cat jumped out of Peter's arms and made a noise (I think it knock something over or something fell) which confirmed the burglars suspicions that someone was up there. So in turn, they turned Anne and her family in for the reward.

Well that's the story I always got, anyway.

All typos and misspellings courtesy of a public educational system.

Surveys says, Voskuijl's (Miep's husband) sister, fond of the Nazis, snitched them. She only died in 2001. More here:http://www.nltimes.nl/2015/04/07/sister-of-anne-frank-helper-likely-betrayed-frank-family-book/