In the years 1945-1950 the Germans who did not leave Lower Silesia were in the area of interest of the District Security Office and their local agencies. The Ministry for Public Security in Warsaw instructed their subordinates to carry on 'planned and regular' actions so that to find and destroy 'the revisionist German underground', called 'Wehrwolf'. A similar action was carried on by the Soviet troops in Saxony. It is impossible to estimate how many Germans in Lower Silesia were arrested within the action, because of the residual preservation of files. There is no doubt, however, that one the important operations took place in Boleslawiec where more than 100 Germans were arrested and accused of being members of the organization Freies Deutschland. It is known from documents and memoirs that the evidence was extracted by force. Presumably illegitimate investigation methods from Boleslawiec were practiced also in other places. In the years 1945-1950 the Military District Court in Wroclaw, on the basis of documentation provided by security officers, sentenced 26 Germans for death penalties and others for long-lasting prison penalties. There were found documents in the archive of the Institute of National Remembrance which prove that 11 of the convicted Germans were executed, 2 of them were women. The analysis of the files which are preserved suggests, however, that the presence of 'the German underground' could be only a fictitious idea used for strengthening animosity between Polish newcomers and the German autochthons and accounting for displacing the latter. The result of the investigation was also presented as a quick and spectacular success of the new authorities in the so-called Recovered Lands.