In 1939 Polish teachers created Secret Teaching Organization an underground Polish educational organization to provide underground education in occupied Poland . Thousands of its members were arrested and killed by the Germans . It is estimated that about 15 % of Polish teachers or 8,000 died during the occupation period . Extermination of teachers and scientists was part of a Nazi plan to eliminate all Polish intelligentia during action Intelligenzaktion
Intelligenzaktion
Intelligenzaktion
Polish areas annexed by Nazi Germany