What mistake did Hitler make preparing for war? Why did he make this decision?

After the First World War, the map of Europe was re-drawn and several new countries were formed. As a result of this, three million Germans found themselves now living in part of Czechoslovakia. When Adolf Hitler came to power, he wanted to unite all Germans into one nation.

In September 1938 he turned his attention to the three million Germans living in part of Czechoslovakia called the Sudetenland. Sudeten Germans began protests and provoked violence from the Czech police. Hitler claimed that 300 Sudeten Germans had been killed. This was not actually the case, but Hitler used it as an excuse to place German troops along the Czech border.

During this situation, the British Prime Minister, Neville Chamberlain, flew to meet Hitler at his private mountain retreat in Berchtesgaden in an attempt to resolve the crisis. Three of the documents here are extracts from Chamberlain's own record of the meeting. The other two documents are useful evidence of the kind of advice Chamberlain was getting at home in Britain.