The German authorities engaged in a systematic effort to destroy Polish culture and national identity. During operation AB-Aktion, many university professors and members of the Polish intelligentsia were arrested, transported to concentration camps, or executed. During the war, Poland lost an estimated 39 to 45 percent of its physicians and dentists, 26 to 57 percent of its lawyers, 15 to 30 percent of its teachers, 30 to 40 percent of its scientists and university professors, and 18 to 28 percent of its clergy.[338]