Britain and France guarantee the integrity of Poland's borders after Hitler violates Munich Agreement of 1938 by invading and dismembering Czechoslovakia. In September, Germany invades Poland, starting World War II in Europe. In response, Great Britain, France, and the British Dominions declare war on Germany. In November, the first ghetto is established in Piotrków, Poland. Jews in parts of occupied Poland are forced to wear armbands bearing the Star of David for identification.