Question: What year did Heinrich Himmler join the unit that used the concept of Wehrbauer to refer to soldiers designated as settlers for the lands conquered during the German invasions of the Soviet Union and Poland?

full_context: Document 1: Forced labor of Germans in the Soviet Union: Forced labor of Germans in the Soviet Union was considered by the Soviet Union to be part of German war reparations for the damage inflicted by Nazi Germany on the Soviet Union during World War II. German civilians in Eastern Europe were deported to the USSR after World War II as forced laborers. Ethnic Germans living in the USSR were deported during World War II and conscripted for forced labor. German prisoners of war were also used as a source of forced labor during and after the war by the Soviet Union and the Western Allies.
Document 2: Sicherheitsdienst: Sicherheitsdienst (] , "Security Service"), full title Sicherheitsdienst des Reichsführers-SS (English: Security Service of the Reichsführer-SS ), or SD, was the intelligence agency of the SS and the Nazi Party in Nazi Germany. The organization was the first Nazi Party intelligence organization to be established and was considered a sister organization with the Gestapo , which the SS had infiltrated heavily after 1934. Between 1933 and 1939, the SD was administered as an independent SS office, after which it was transferred to the authority of the Reich Main Security Office ("Reichssicherheitshauptamt "; RSHA), as one of its seven departments/offices. Its first director, Reinhard Heydrich , intended for the SD to bring every single individual within the Third Reich's reach under "continuous supervision."
Document 3: Bergbauernhilfe: Bergbauernhilfe (BBH)– ("mountain-peasant’s help") – codename of the Abwehr II subversive operations unit of 120 men recruited from the OUN members. It was established on August 15, 1939. This unit was disbanded on September 28 of the same year, and Abwehr was ordered to cease contacts with Ukrainian Nationalists with the advent of the Molotov-Ribbentrop Pact.
Document 4: Obergruppenführer: Obergruppenführer (] , "senior group leader") was a Nazi Party paramilitary rank that was first created in 1932 as a rank of the "Sturmabteilung" (SA), and adopted by the "Schutzstaffel" (SS) one year later. Until April 1942, it was the highest commissioned SS rank, inferior only to "Reichsführer-SS" (Heinrich Himmler or RFSS, which was the internal SS-abbreviation for Himmler) Translated as "senior group leader", the rank of "Obergruppenführer" was senior to "Gruppenführer". A similarly named rank of "Untergruppenführer" existed in the SA from 1929 to 1930 and as a title until 1933. In April 1942, the new rank of "SS-Oberst-Gruppenführer" was created which was above "Obergruppenführer" and below "Reichsführer-SS".
Document 5: Gestapo: The Gestapo (] ), abbreviation of Geheime Staatspolizei, or the Secret State Police, was the official secret police of Nazi Germany and German-occupied Europe.
Document 6: Ernst Röhm: Ernst Julius Günther Röhm (] ; 28 November 1887 – 1 July 1934) was a German military officer and an early member of the Nazi Party. As one of the members of its predecessor, the German Workers' Party, he was a close friend and early ally of Adolf Hitler and a co-founder of the "Sturmabteilung " (SA, "Storm Battalion"), the Nazi Party's militia, and later was its commander. By 1934, the German Army feared the SA's influence and Hitler had come to see Röhm as a potential rival, so he was executed during the Night of the Long Knives.
Document 7: Wehrbauer: Wehrbauer (] , "soldier peasant") was a concept used by the "Schutzstaffel" (SS) of the Nazi Party to refer to soldiers designated as settlers for the lands conquered during the German invasions of the Soviet Union and Poland.
Document 8: Mann (military rank): Mann (German for "man", "male", "husband", or "fellow"), was a paramilitary rank used by several Nazi Party paramilitary organizations between 1925 and 1945. The rank is most often associated with the SS, and also as a rank of the SA where "Mann" was the lowest enlisted rank and was the equivalent of a private.
Document 9: Volkssturm: The Volkssturm (] , "people's storm") was a national militia established by Nazi Germany during the last months of World War II. It was not set up by the German Army, the ground component of the combined German Wehrmacht armed forces, but by the Nazi Party on the orders of Adolf Hitler and its official existence was not announced until 16 October 1944. It was staffed by conscripting males between the ages of 16 and 60 years who were not already serving in some military unit as part of a German Home Guard. The "Volkssturm" comprised one of the final components of the Total War promulgated by Propaganda Minister Joseph Goebbels, part of a Nazi endeavor to overcome their enemies' military strength through force of will.
Document 10: Schutzstaffel: The Schutzstaffel (SS; also stylized as with Armanen runes; ] ; literally "Protection Squadron") was a major paramilitary organization under Adolf Hitler and the Nazi Party (NSDAP) in Nazi Germany, and later throughout German-occupied Europe during World War II. It began with a small guard unit known as the "Saal-Schutz" (Hall-Protection) made up of NSDAP volunteers to provide security for party meetings in Munich. In 1925, Heinrich Himmler joined the unit, which had by then been reformed and given its final name. Under his direction (1929–45), it grew from a small paramilitary formation to one of the most powerful organizations in Nazi Germany. From 1929 until the regime's collapse in 1945, the SS was the foremost agency of security, surveillance, and terror within Germany and German-occupied Europe.
Document 11: Leibstandarte SS Adolf Hitler order of battle: The Leibstandarte SS "Adolf Hitler" (LSSAH) was founded in September 1933 as Adolf Hitler's personal Bodyguard formation. It was given the title "Leibstandarte Adolf Hitler" (LAH) in November, 1933. On 13 April 1934, by order of Himmler, the regiment became known as the "Leibstandarte SS Adolf Hitler" (LSSAH). In 1939 the LSSAH became a separate unit of the Waffen-SS aside the SS-TV and the SS-VT.
Document 12: Volkssturmgewehr: The Volkssturmgewehr ("People's Assault Rifle") is the name of several rifle designs developed by Nazi Germany during the last months of World War II. They share the common characteristic of being greatly simplified as an attempt to cope with severe lack of resources and industrial capacity in Germany during the final period of the war.
Document 13: Sturmabteilung: The Sturmabteilung (SA; ] ), literally Storm Detachment, functioned as the original paramilitary wing of the Nazi Party (NSDAP).
Document 14: Hegewald (colony): Hegewald was a short-lived German colony during World War II, situated near Zhytomyr in Reichskommissariat Ukraine. It was repopulated in late 1942 and early 1943 by the ethnically German settlers classified as "Volksdeutsche"; transferred from occupied territories of Poland, Croatia, Bessarabia, and the Soviet Union to an area earmarked for the projected Germanization of the Ukrainian lands. The plans were prepared months in advance by the SS, RKFDV and VoMi, but major problems with supplies occurred right from the region's initial establishment. Heinrich Himmler's original plans to recruit settlers from Scandinavia and the Netherlands were unsuccessful.
Document 15: Stasi: The Ministry for State Security (German: "Ministerium für Staatssicherheit" , MfS) or State Security Service ("Staatssicherheitsdienst", SSD), commonly known as the Stasi (] ), was the official state security service of the German Democratic Republic (East Germany). It has been described as one of the most effective and repressive intelligence and secret police agencies to have ever existed. The Stasi was headquartered in East Berlin, with an extensive complex in Berlin-Lichtenberg and several smaller facilities throughout the city. The Stasi motto was ""Schild und Schwert der Partei"" (Shield and Sword of the Party), referring to the ruling Socialist Unity Party of Germany (German: "Sozialistische Einheitspartei Deutschlands", SED). Erich Mielke was its longest-serving chief, in power for thirty-two of the GDR's forty years of existence.
ground_truth: 1925