This was a German operation to seize members of the Polish intelligentsia teaching at universities in the city of Kraków (6 November 1939).
The undertaking was part of the much broader plan, the 'Intelligenzaktion', schemed for the eradication the Polish intellectual elite, especially in the cities scheduled to become culturally German.
A little more than two months after the German 'Weiss' (i) invasion and conquest of Poland, the Gestapo chief in Kraków, SS-Obersturmbannführer Bruno Müller, ordered the rector of the Jagiellonian University, Professor Tadeusz Lehr-Spławiński, to require all professors to attend his lecture about German plans for Polish education. Lehr-Spławiński necessarily agreed and sent invitations throughout the university to a meeting at the administrative centre building in the Collegium Novum. At 12.00 on 6 November 1939, the academics and their guests gathered, their number including 105 professors and 33 lecturers of the Jagiellonian University, 34 professors and doctors from University of Technology, some of whom attended a meeting in a different room, four from University of Economics and four from Lublin and Wilno.
The academics filled the hall, but instead of hearing a lecture, they were told by Müller that the university did not have permission to start a new academic year, and that Poles were hostile toward German science, and acted in bad faith. The academics were arrested and escorted out of the hall, some senior professors being kicked, slapped and hit with rifle butts. Another 13 to 15 university employees and students, who happened to be in the area, were also seized, and the president of Kraków, Dr Stanisław Klimecki, was arrested at home during the afternoon of the same day.
All 184 arrested persons were taken first to the prison in Montelupich street, then to the barracks at Mazowiecka, and three days later to a detention centre in Breslau, where they spent 18 days split between two prison facilities. The Gestapo was not ready to handle the the influx of so many prisonsrs at one time, and awaited permission to send them to Buchenwald concentration camp, which was already full to capacity. As a result, during the night of 27/28 November, the prisoners were loaded onto a train and sent to Sachsenhausen concentration camp, and thence in March 1940 to Dachau concentration camp near Munich after a new batch of younger academics had been seized and sent to join the first group.
After a major international protest by prominent Italians, including Benito Mussolini and the Vatican, professors over the age of 40 were released from Sachsenhausen on 8 February 1940, and other academics were released at a later date. Many of the elderly professors, however, had not survived the twice-daily roll calls day in snow and rain, and the grim living conditions in the camp, where dysentery was rife and warm clothes rare: 12 died in the camp within three months of their arrival, and another five within days of their release.
In March 1940 the prisoners from Kraków who remained alive were sent to Dachau concentration camp, from which most but not all, were released in January 1941.
Many of those who went through the 'Sonderaktion Krakau' and the internment in 1942 formed an underground university in defiance of the German punitive edicts.