The first pogroms were made by Wehrmacht units and Sipo Einsatzgruppen . They arrested and executed political , social , and cultural activists as well as local government officials . Offices , institutions , and locations of Polish social and political organisations were penetrated . This action was codenamed Operation Tannenberg . Goals were the liquidation of intellectual elites , and destruction of Polish culture , institutions and organisations . Operational groups and Selbstschutz received orders to " politically cleanse the areas " . The first arrests of Poles started after Wehrmacht arrived in Free City of Danzig ( Gdańsk ) on 1 September 1939 . With the help of units from SA , SS , and local police Polish officies and institutions were taken over . Polish State Railways workers and custom officers were executed in Szymanków , Kałdów , or in their offices
Operation Tannenberg
Operation Tannenberg
History of Pomerania (1933–1945)