Communists vs. "Reactionary Underground" in Stalinist Poland
In post-World War II Poland, the Office of State Security (UB or 'the Office') focused its attention to what was called the reactionary underground." The Communists, who ran the Provisional Government, struggled with the opposition. It was the armed resistance, however, that was the Provisional Governments hated rival.
Communists fight Home Army in Polish "civil war"