tens of thousands were sentenced by courts on fabricated and arbitrary charges or deported to the Soviet Union. The status of Soviet troops in Poland was not legalized until late 1956, when the Polish-Soviet declaration "On the legal status of Soviet forces temporarily stationed in Poland" was signed. The Soviet Northern Group of Forces would be permanently stationed in Poland. Rigged elections, defeat of Mikołajczyk Stalin had promised at the Yalta Conference that free elections would be held in Poland. However, the Polish communists, led by Gomułka and Bierut, while having no intention of giving up power, were also aware of the limited support they enjoyed among the general population. To circumvent this difficulty, in 1946 a national plebiscite, known as the "Three Times Yes" referendum (Trzy razy tak), was held first, before the parliamentary elections. The referendum comprised three fairly general, but politically charged questions about the Senate, national industries and western borders. It was meant to check and promote the popularity of communist initiatives in Poland. Since most of the important parties at the time were leftist or centrist – and could have easily approved all three options – Mikołajczyk's Polish People's Party (PSL) decided, not to be seen as merging into the government bloc, to ask its supporters to oppose the first one: the abolition of the Senate. The communists voted "Three Times Yes". The partial results, reconstructed by the PSL, showed that the communist side was met with little support on the first question. However, after a campaign marked by electoral fraud and intimidation the communists claimed large majorities on all three questions, which led to the nationalization of industry and state control of economic activity in general, and a unicameral national parliament (Sejm). The communists consolidated power by gradually whittling away the rights of their non-communist foes, particularly by suppressing the leading opposition party – Mikołajczyk's PSL. In some widely publicized cases, the perceived enemies were sentenced to death on trumped up charges — among them Witold Pilecki, the organizer of the Auschwitz resistance. Leaders of the Home Army and of the Council of National Unity were persecuted. Many resistance fighters were murdered extrajudicially or forced to exile. The opposition members were also harassed by administrative means. Although the ongoing persecution of the former anti-Nazi and right-wing organizations by state security kept some partisans in the forests, the actions of the Ministry of Public Security