The Polish resistance movement was active in the city. Several organizations were formed in Poznań, including Tajna Polska Organizacja Wojskowa (Secret Polish Military Organization), (Poznań Military Organization), (National Fighting Organization), Ojczyzna (Homeland) and Komitet Niesienia Pomocy (Relief Committee), with some later merged into larger structures. Regional branches of the nationwide Union of Armed Struggle, Bataliony Chłopskie, Gray Ranks and organizations were also founded. Activities included secret Polish schooling, printing and distribution of underground Polish press, sabotage actions, military trainings, espionage of German activity, providing aid to people in need, preparations for a planned uprising, and facilitating escapes of British prisoners of war from Stalag XXI-D. In June 1940, the Bureau of the Government Delegation for Poland for Polish territories annexed by Germany was founded, and in July 1940, even an underground Polish parliament was established in Poznań. The Germans cracked down on Polish resistance several times, with many Poles either executed or tortured and killed in prisons and concentration camps. In February 1943, a flying unit of the Union of Armed Struggle and Home Army carried out an operation to burn down Wehrmacht warehouses in the local river port, an action deemed one of the most spectacular in the region.
