There are also numerous incidents of Jews who survived the concentration camps returning to their homes, only to be murdered by the Polish families now living in those homes. Estimates run between 1000 and 2000 dead.
Unlike in most European countries occupied by Nazi Germany—where the Germans sought and found true collaborators among the locals—in occupied Poland there was no official collaboration either at the political or at the economic level.[66][67] Poland also never officially surrendered to the Germans.[68] Under German occupation, the Polish army continued to fight underground, as Armia Krajowa and forest partisans – Leśni. The Polish resistance movement in World War II in German-occupied Poland was the largest resistance movement in all of occupied Europe.[69] As a result, Polish citizens were unlikely to be given positions of any significant authority.[66][67] The vast majority of the pre-war citizenry collaborating with the Nazis was the German minority in Poland which was offered one of several possible grades of German citizenship.[70] In 1939, before the German invasion of Poland, 800,000 people declared themselves as members of the German minority in Poland mostly in Pomerania and Western Silesia. During the war there were about 3 million former Polish citizens of German origin who signed the official list of Volksdeutsche.[67] People who became Volksdeutsche were treated by Poles with special contempt, and the fact of them having signed the Volksliste constituted high treason according to the Polish underground law.
There is a general consensus among historians that there was very little collaboration with the Nazis among the Polish nation as a whole, compared to other German-occupied countries.[66][67][71] Depending on a definition of collaboration (and of a Polish citizen, based on ethnicity and minority status), scholars estimate number of "Polish collaborators" at around several thousand in a population of about 35 million (that number is supported by the Israeli War Crimes Commission).[72] The estimate is based primarily on the number of death sentences for treason by the Special Courts of the Polish Underground State. Some estimates are higher, counting in all members of the German minority in Poland and any former Polish citizens declaring their German ethnicity (Volksdeutsche), as well as conscripted members of the Blue Police, low-ranking Polish bureaucrats employed in German occupational administration, and even workers in forced labor camps (ex. Zivilarbeiter and Baudienst). Most of the Blue Police were forcibly drafted into service; nevertheless, a significant number acted as spies for Polish resistance movement Armia Krajowa.[71] John Connelly quoted a Polish historian (Leszek Gondek) calling the phenomenon of Polish collaboration "marginal" and wrote that "only relatively small percentage of Polish population engaged in activities that may be described as collaboration when seen against the backdrop of European and world history".[71]
In October 1939, the Nazis ordered the mobilization of the pre-war Polish police to the service of the occupational authorities. The policemen were to report for duty or face the death penalty, thus forming the so-called Blue Police.[73] At its peak in 1943, it numbered around 16,000.[74] Its primary task was to act as a regular police force and to deal with criminal activities, but were also used by the Germans in combating smuggling, resistance, and in measures against the Polish (and Polish Jewish) population: for example, it was present in łapankas (rounding up random civilians for labor duties) and patrolling for Jewish escapees from the ghettos. Nonetheless many individuals in the Blue Police followed German orders reluctantly, often disobeyed German orders or even risked death acting against them.[75][76][77] Many members of the Blue Police were in fact double agents for the Polish resistance.[78][79] Some of its officers were ultimately awarded the Righteous among the Nations awards for saving Jews.[80][81]
Following Nazi Germany's attack on the Soviet Union in June 1941, German forces quickly overran the territory of Poland controlled by the Soviets since their joint invasion of Poland in accordance with the Molotov-Ribbentrop Pact. A number of people collaborating with the Soviets before Operation Barbarossa were killed by local people. Belief in the Żydokomuna stereotype, combined with the German Nazi encouragement for expression of anti-Semitic attitudes, was a principal cause of massacres of Jews by gentile Poles in Poland's northeastern Łomża province in the summer of 1941, including the massacre at Jedwabne.[82][83]
However, research shows that at least as far as Warsaw is concerned, the number of Poles aiding Jews far outnumbered those who sold out their Jewish neighbours to the Nazis. According to the studies of historian Gunnar S. Paulsson, during the Nazi occupation of Warsaw 70,000–90,000 Polish Gentiles aided Jews, while 3,000–4,000 were szmalcowniks, or blackmailers who collaborated with the Nazis in persecuting the Jews.[84]
Two members of the Jewish Ghetto Police guarding the gates of the Warsaw Ghetto, June 1942 The collaboration by some Polish Jews, who belonged to Żagiew and Group 13 inflicted considerable damage to both Jewish and Polish underground movements, as members of the collaborationist groups acted as informants for the Germans, revealing the organized efforts by the resistance to hide Jews,[85] and engaged in racketeering, blackmail and extortions inside the Warsaw Ghetto.[86][87]
Also, the Jewish Ghetto Police was recruited form among Polish Jews living inside the ghettos who could be relied upon to follow German orders. Members of Jüdischer Ordnungsdienst were issued batons, identifying armband, hats and badges, they were used by the Germans primarily for securing the deportation of other Jews to concentration camps, but their work encompassed all forms of public order in the Ghetto.[88] The Polish-Jewish historian and Warsaw Ghetto archivist Emanuel Ringelblum described the cruelty of the ghetto police as "at times greater than that of the Germans.".[89] The size of each police outfit inside a ghetto varied greatly, with the Warsaw Ghetto having about 2,500 active members, Łódź Ghetto 1,200 and smaller ghettos like that in the city of Lwów had around 500 Jewish policeman.[90]
One partisan unit of Polish right-wing National Armed Forces, the Holy Cross Mountains Brigade, decided to tacitly cooperate with the Germans in late 1944. It ceased hostile actions against the Germans for a few months, accepted logistic help and withdrew from Poland into Czechoslovakia with German approval in late stages of the war in order to avoid capture by the Soviets. Once in Czechoslovakia, the unit resumed hostilities against the Germans and on May 5 liberated the concentration camp at Holýšov.[91]
In 1944 Germans clandestinely armed a few regional Armia Krajowa (AK) units operating in the area of Vilnius in order to encourage them to act against the Soviet partisans in the region; in Nowogrodek district and to a lesser degree in Vilnius district (AK turned these weapons against the Nazis during Operation Ostra Brama).[48][92] Such arrangements were purely tactical and did not evidence the type of ideological collaboration as shown by Vichy regime in France or Quisling regime in Norway.[75] The Poles main motivation was to gain intelligence on German morale and preparedness and to acquire much needed equipment.[93] There are no known joint Polish-German actions, and the Germans were unsuccessful in their attempt to turn the Poles toward fighting exclusively against Soviet partisans.[75] Further, most of such collaboration of local commanders with the Germans was condemned by AK headquarters.[75] Tadeusz Piotrowski quotes Joseph Rothschild saying "The Polish Home Army was by and large untainted by collaboration" and adds that "the honor of AK as a whole is beyond reproach".[75]