at Mazowiecka, and—three days later—to a detention center in Breslau, Germany (now Wrocław, Poland), where they spent 18 days split between two prison facilities: the detention center (Untersuchungsgefängnis, at the Świebodzka 1 Street), and the Strafgefängnis penal complex at Kleczkowska 35. The Gestapo were unprepared for such a large transfer of prisoners, and awaited permission to send them to Buchenwald concentration camp. However, that was filled to capacity and so, on 27 November 1939, at night, they were loaded onto a train to Sachsenhausen concentration camp located on the other side of Berlin, and in March 1940, sent further to Dachau concentration camp near Munich after a new batch of arrested younger academics arrived. Release Following loud international protest by prominent Italians including Benito Mussolini and the Vatican, 101 professors who were older than 40 were released from Sachsenhausen on 8 February 1940. Additional academics were released later. Some elderly professors did not survive the roll-calls, held three times a day even in ice and snow, and the grim living conditions where dysentery was common, warm clothes rare and food rations scarce. Twelve died in the camp within three months, and another five within weeks of release. Three professors of Jewish origin were separated and later were murdered or died of other causes: (Leon Sternbach, Wiktor Ormicki and ). Among the notable professors who died in the camp were Ignacy Chrzanowski (UJ; 19 January 1940), Stanisław Estreicher (UJ; 29 December 1939), Kazimierz Kostanecki (UJ; 11 January 1940), (AGH; 24 December 1939) and Michał Siedlecki (UJ; 11 January 1940, after roll-call). In March 1940, the able prisoners from Kraków who remained alive were sent to Dachau concentration camp and most released in January 1941 on intervention. The last one, Kazimierz Piwarski, was released in late 1941. Many of those who went through Sonderaktion Krakau and the internment formed an underground university in 1942 in defiance of the German punitive edicts. Among the 800 students of their underground college was Karol Wojtyła, the future Pope John Paul II, taught by Prof. Tadeusz Lehr-Spławiński among others. Today there is a plaque commemorating the events of Sonderaktion Krakau in front of Collegium Novum in Kraków. Every 6 November, black flags are hung outside all Jagiellonian University buildings, and the Rector of the University lays wreaths to honor those who suffered. Prominent personalities arrested during Sonderaktion Krakau Below is a partial list of selected prominent