In March 1940, a partisan unit of the first guerilla organisation of the Second World War in Europe, led by Major Henryk Dobrzański (Hubal) completely destroyed a battalion of German infantry in a skirmish near the village of Huciska. A few days later in an ambush near the village of Szałasy it inflicted heavy casualties upon another German unit. To counter this threat, the German authorities formed a special 1,000 man-strong anti-partisan unit of combined SS-Wehrmacht forces, including a Panzer group. Although Dobrzański's unit never exceeded 300 men, the Germans fielded at least 8,000 men in the area to secure it.
In 1940, Witold Pilecki, a member of Polish resistance, presented to his superiors a plan to enter Germany's Auschwitz concentration camp, gather intelligence on the camp from the inside, and organize inmate resistance. The Home Army approved this plan, provided him with a false identity card, and on 19 September 1940, he deliberately went out during a street roundup in Warsaw-łapanka, and was caught by the Germans along with other civilians and sent to Auschwitz. In the camp he organized the underground organization Związek Organizacji Wojskowej (ZOW). From October 1940, ZOW sent the first reports about the camp and its genocide to Home Army Headquarters in Warsaw through the resistance network organized in Auschwitz.
On the night of January 21–22, 1941, in the Soviet-occupied Podolian town of Czortków, the Czortków Uprising started. It was the first Polish uprising and the first anti-Soviet uprising of World War II. Anti-Soviet Poles, most of them teenagers from local high schools, stormed the local Red Army barracks and a prison, in order to release Polish soldiers kept there.