Jewish Military Union
Within some of the destroyed suburbs, a limited postal system between various Robinson groups was established. Dawid Landau had served as a bodyguard to the courier of the Polish government in exile, Jan Karski, while Karski secretly entered the ghetto to gather information for a report on the extermination of Polish Jews by Nazi Germany for the Western allies, in 1943. Later, Landau fought in both of the Warsaw uprising as part of Żydowski Związek Wojskowy (Jewish Military Union, ŻZW) and afterward decided to stay in the ruins. In his memoirs he reports that the post functioned through the use of empty electrical socket boxes. Various groups would leave notes for others informing them of who was alive and in hiding, news from the front that had been obtained, as well as requests for special forms of assistance. According to Landau, the most common pleas were for doctors or other forms of medical help.