The organization of underground resistance movements in Auschwitz concentration camp began in the second half of 1940, shortly after the camp became operational in May that year.[1][2] In September 1940 Witold Pilecki, a Polish army captain, arrived in the camp. Using the name Tomasz Serafiński (prisoner number 4859), Pilecki had allowed himself to be captured by Germans in a street round up (łapanka) with the goal of having himself sent to Auschwitz to gather information and organize resistance inside.[2][3] Under Pilecki's direction the Związek Organizacji Wojskowej (Union of Military Organization), ZOW, was formed.[3]