of Polish intelligentsia, politicians, civil servants and scientists, but also ordinary people suspected of posing a threat to the Soviet rule. Among the arrested members of the Polish intelligentsia were former prime ministers Leon Kozłowski and Aleksander Prystor, as well as Stanisław Grabski, Stanisław Głąbiński and the Baczewski family. Initially aimed primarily at possible political opponents, by January 1940 the NKVD aimed its campaign also at its potential allies, including the Polish communists and socialists. Among the arrested were Władysław Broniewski, Aleksander Wat, Tadeusz Peiper, Leopold Lewin, Anatol Stern, Teodor Parnicki, Marian Czuchnowski and many others. Deportation In 1940 and the first half of 1941, the Soviets deported more than 1,200,000 Poles, most in four mass deportations. The first deportation took place 10 February 1940, with more than 220,000 sent to northern European Russia; the second on 13 April 1940, sending 320,000 primarily to Kazakhstan; a third wave in June–July 1940 totaled more than 240,000; the fourth occurred in June 1941, deporting 300,000. Upon resumption of Polish-Soviet diplomatic relations in 1941, it was determined based on Soviet information that more than 760,000 of the deportees had died – a large part of those dead being children, who had comprised about a third of deportees. Approximately 100,000 former Polish citizens were arrested during the two years of Soviet occupation. The prisons soon got severely overcrowded. with detainees suspected of anti-Soviet activities and the NKVD had to open dozens of ad hoc prison sites in almost all towns of the region. The wave of arrests led to forced resettlement of large categories of people (kulaks, Polish civil servants, forest workers, university professors or osadniks, for instance) to the Gulag labour camps and exile settlements in remote areas of the Soviet Union. Altogether roughly a million people were sent to the east in four major waves of deportations. According to Norman Davies, almost half of them were dead by the time the Sikorski-Mayski Agreement had been signed in 1941. According to the Soviet law, all residents of the annexed area, dubbed by the Soviets as citizens of former Poland, automatically acquired Soviet citizenship. However, actual conferral of citizenship still required the individual's consent and the residents were strongly pressured for such consent. The refugees who opted out were threatened with repatriation to Nazi controlled territories of Poland. Exploitation of ethnic tensions In addition, the Soviets exploited past ethnic tension between Poles and other