The Urząd Bezpieczeństwa was involved in agent activities, surveillance, terror against Home Army soldiers, and the underworld. and opposition politicians.

The Urząd Bezpieczeństwa tried to eliminate the resistance of the “Cursed soldiers” (Polish: Żołnierze wyklęci) who were opposing the communist authorities by armed combat, targeting communist army officers, UBagents, communist state officials and the communist police, the Milicja Obywatelska. The Urząd Bezpieczeństwa participated in the countryside during forced collectivization and fought against the influence of the Catholic Church.

Infiltrated by NKGB and NKVD agents – the Ministry of Public Security was well known for its criminal nature. From January 1945 (or, July 22), the surviving members of the Home Army laid down their arms, granted an official amnesty (lasting till October 15).

Most were arrested by MBP on the spot, tortured and tried for treason. The MBP carried out brutal pacification of civilians, mass arrests (see: Augustów roundup), as well as makeshift executions (see: Mokotów Prison murder, Public execution in Dębica) and secret assassinations.

According to depositions by Józef Światło and other communist sources, in 1945 alone the number of members of the Polish Underground State deported to Siberia and various labor camps in the Soviet Union reached 50,000.

Overall, in the years 1944–1956 around 300,000 Polish citizens had been arrested, of whom many thousands were sentenced to long-term imprisonment. There were 6,000 death sentences pronounced, the majority of them carried out “in the majesty of the law”.

A special disciplinary legislation had been introduced, which allowed for the sentencing of civil persons before military tribunals including young people and children. The courts were concerned with the alleged crimes, not the age and the maturity of its victims.

For many years, the public prosecutors and judges as well as functionaries of the Ministry of Public Security, Security Service of the Ministry of Internal Affairs (SB) and Main Directorate of Information of the Polish Army (GZI WP) engaged in acts recognized by international law as crimes against humanity and crimes against peace.

The so-called “Cursed soldiers” of the anti-communist resistance, who opposed the new occupiers and attacked the Stalinist strongholds, were eventually hunted down by MBP security services and assassination squads.

The underground structures had been destroyed, and most members of the Armia Krajowa and WiN who remained opposed to communism, were executed after kangaroo trials (staged by Wolińska-Brus and Zarakowski among others), or deported to the Soviet GULAG system.

Stalinist secret agents of the Urząd Bezpieczeństwa (UB) – notice the name changes include Antoni Alster (b. Nachum Alster), Józef Bik (vel Jozef Bukar, vel Jozef Gawerski), Józef Czaplicki (b. Izydor Kurc), Julian Kole, Julian Konar (b. Jakub Kohn), Grzegorz Korczyński, Mieczysław Mietkowski (b. Mojżesz Bobrowicki), Henryk Pałka, Julian Polan-Haraschin, Leon Rubinstein and Mieczysław Moczar.