> Neville Chamberlain and France had given Hitler chances before Germany invaded Poland and didn’t stand up to him, which made him more aggressive. For example, the remilitarisation of the Rhineland was not opposed, which lead to Hitler invading other lands.
When Germany took over the Sudetenland, Britain and France had agreed to let him keep the land at the Munich conference, and Hitler betrayed that agreement when he took over the rest of Czechoslovakia.