 Complete the following phrase:  During the German invasion of Poland, which started World War II, the Germans carried out mass arrests of local Poles. On September 1, 1939, the day of the outbreak of the war, Adam Bożek, the chairman of the Upper Silesian district of the Union of Poles in Germany, was arrested in Bytom and then deported to the Dachau concentration camp. The Germans carried out revisions in the Polish gymnasium and the local Polish community centre, 20 Polish activists were arrested on September 4, 1939, then released and arrested again a few days later to be deported to the Buchenwald concentration camp. Also three Polish teachers, who had not yet fled, were arrested, while the assets of the Polish bank were confiscated. The Einsatzgruppe I entered the city on September 6, 1939, to commit 