Question: Walloon Legion, a collaborationist volunteer unit, that served on the Eastern Front, in which war?

full_context: Document 1: Wolf's Lair: Wolf's Lair (German: "Wolfsschanze"; Polish: "Wilczy Szaniec") was Adolf Hitler's first Eastern Front military headquarters in World War II. The complex, which became one of several "Führerhauptquartiere" (Führer Headquarters) in various parts of eastern Europe, was built for the start of Operation "Barbarossa" – the invasion of the Soviet Union – in 1941. It was constructed by Organisation Todt.
Document 2: Armenische Legion: The 812th Armenian Battalion (German: "Armenische Legion" ; Armenian: Հայկական լեգիոն "Haykakan legion"), also known as the Armenian Legion, was a military unit in the German Army during World War II. It primarily consisted of Soviet Armenian, who had been taken prisoner by the Nazis, and commanded by General Drastamat Kanayan.
Document 3: Operation Citadel: Operation Citadel (German: "Unternehmen Zitadelle" ) was a German offensive operation against Soviet forces in the Kursk salient during the Second World War on the Eastern Front that initiated the Battle of Kursk. The deliberate defensive operation that the Soviets implemented to repel the German offensive is referred to as the Kursk Strategic Defensive Operation. The German offensive was countered by two Soviet counter-offensives, Operation Polkovodets Rumyantsev (Russian: Полководец Румянцев ) and Operation Kutuzov (Russian: Кутузов ). For the Germans, the battle was the final strategic offensive that they were able to launch on the Eastern Front. As the Allied invasion of Sicily began Adolf Hitler was forced to divert troops training in France to meet the Allied threats in the Mediterranean, rather than use them as a strategic reserve for the Eastern Front. Germany's extensive loss of men and tanks ensured that the victorious Soviet Red Army enjoyed the strategic initiative for the remainder of the war.
Document 4: Battle of Kursk: The Battle of Kursk was a Second World War engagement between German and Soviet forces on the Eastern Front near Kursk (450 km south-west of Moscow) in the Soviet Union during July and August 1943. The battle began with the launch of the German offensive, Operation Citadel (German: "Unternehmen Zitadelle" ), on 5 July, which had the objective of pinching off the Kursk salient with attacks on the base of the salient from north and south simultaneously. After the German offensive stalled on the northern side of the salient, on 12 July the Soviets commenced their Kursk Strategic Offensive Operation with the launch of Operation Kutuzov (Russian: Кутузов ) against the rear of the German forces in the northern side. On the southern side, the Soviets also launched powerful counterattacks the same day, one of which led to a large armoured clash, the Battle of Prokhorovka. On 3 August, the Soviets began the second phase of the Kursk Strategic Offensive Operation with the launch of Operation Polkovodets Rumyantsev (Russian: Полководец Румянцев ) against the German forces in the southern side of the Kursk salient.
Document 5: Croatian Air Force Legion: The Croatian Air Force Legion (Croatian: "Hrvatska Zrakoplovna Legija" ), or HZL, also known as the Croatian Legion, was a foreign volunteer unit of the Luftwaffe raised from volunteers drawn from the Independent State of Croatia which fought on the Eastern Front between 1941–1943 in the Second World War. It was then absorbed by the Air Force of the Independent State of Croatia and its surviving members fought back on Croatian soil. The legion had approximately 360 men.
Document 6: 2nd SS Panzer Division Das Reich: The 2nd SS Panzer Division "Das Reich" was a division of the Nazi Waffen-SS during World War II. It was one of the thirty-eight divisions fielded by the Waffen-SS. "Das Reich" served during the invasion of France and took part in several major battles on the Eastern Front, including in the Battle of Prokhorovka against the 5th Guards Tank Army at the Battle of Kursk. It was then transferred to the West and took part in the fighting in Normandy and the Battle of the Bulge, ending the war in Hungary and Austria. "Das Reich" committed the Oradour-sur-Glane and Tulle massacres.
Document 7: World War II: World War II (often abbreviated to WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945, although related conflicts began earlier. It involved the vast majority of the world's countries—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis. It was the most widespread war in history, and directly involved more than 100 million people from over 30 countries. In a state of total war, the major participants threw their entire economic, industrial, and scientific capabilities behind the war effort, erasing the distinction between civilian and military resources.
Document 8: Eastern Front (World War II): The Eastern Front of World War II was a theatre of conflict between the European Axis powers and co-belligerent Finland against the Soviet Union, Poland and other Allies, which encompassed Northern, Southern and Central and Eastern Europe from 22 June 1941 to 9 May 1945. It has been known as the Great Patriotic War (Russian: Великая Отечественная Война , "Velikaya Otechestvennaya Voyna") in the former Soviet Union, while in Germany it was called the Eastern Front (German: "die Ostfront" ), the Eastern Campaign ("der Ostfeldzug"), the Russian Campaign ("der Rußlandfeldzug"), or the German-Soviet War by outside parties.
Document 9: Legion of French Volunteers Against Bolshevism: The Legion of French Volunteers Against Bolshevism (French: "Légion des volontaires français contre le bolchévisme" , or simply "Légion des volontaires français", LVF) was a collaborationist French militia founded on 8 July 1941. It gathered various collaborationist parties, including Marcel Bucard's "Mouvement Franciste", Marcel Déat's National Popular Rally, Jacques Doriot's French Popular Party, Eugène Deloncle's Social Revolutionary Movement, Pierre Clémenti's French National-Collectivist Party and Pierre Costantini's French League. It had no formal link with the Vichy regime, even though it was recognized as an "association of public usefulness" by Pierre Laval's government in February 1943. Philippe Pétain, head of state of Vichy France, personally disapproved of Frenchmen wearing German uniforms and never went beyond individual and informal words of support to some specific officers.
Document 10: Walloon Legion: The Walloon Legion (French: "Légion Wallonie" ) was a collaborationist volunteer unit recruited from Belgium's French-speaking population in Wallonia and Brussels during the German occupation of World War II. The Walloon Legion served in the Wehrmacht, later in the Waffen-SS, on the Eastern Front on both front line and reserve duties.
Document 11: Eastern Front Medal: The Eastern Front Medal (German: "Medaille „Winterschlacht im Osten 1941/42“" ) was a World War II German military decoration awarded to both German and Axis personnel. It was awarded to those who served on the German Eastern Front during the winter campaign period of 15 November 1941 to 15 April 1942. It was instituted on 26 May 1942 and was commonly known as the "Ostmedaille" (East Medal) or "Russian Front Medal".
Document 12: Battle of Stalingrad: The Battle of Stalingrad (23 August 1942 – 2 February 1943) was a major battle of World War II in which Nazi Germany and its allies fought the Soviet Union for control of the city of Stalingrad (now Volgograd) in Southern Russia.
Document 13: Kaukasisch-Mohammedanische Legion: The Caucasian Muslim Legion (German: "Kaukasische Mohammedaner- Legion/Kaukasische Moslem-Legion") was a volunteer unit of the German Army. The unit was composed of Azerbaijanis, Dagestans, Chechens, Ingushes, and Lezgins.
Document 14: Indian Legion: The Indian Legion (German: "Indische Legion" ), officially the Free India Legion (German: "Legion Freies Indien" ) or Infantry Regiment 950 (Indian) (German: "Infanterie-Regiment 950 (indisches), I.R. 950" ) and later the Indian Volunteer Legion of the Waffen-SS (German: "Indische Freiwilligen Legion der Waffen-SS" ), was a military unit raised during the Second World War in Nazi Germany. Intended to serve as a liberation force for British-ruled India, it was made up of Indian prisoners of war and expatriates in Europe. Because of its origins in the Indian independence movement, it was known also as the "Tiger Legion", and the "Azad Hind Fauj". Initially raised as part of the German Army, it was part of the "Waffen-SS" from August 1944. Indian independence leader Subhas Chandra Bose initiated the legion's formation, as part of his efforts to win India's independence by waging war against Britain, when he came to Berlin in 1941 seeking German aid. The initial recruits in 1941 were volunteers from the Indian students resident in Germany at the time, and a handful of the Indian prisoners of war who had been captured during the North Africa Campaign. It would later draw a larger number of Indian prisoners of war as volunteers.
Document 15: Military history of the Soviet Union: The military history of the Soviet Union began in the days following the 1917 October Revolution that brought the Bolsheviks to power. In 1918 the new government formed the Red Army, which then defeated its various internal enemies in the Russian Civil War of 1917–22. The years 1918–21 saw defeats for the Red Army in the Polish–Soviet War (1919–21) and in independence wars for Estonia (1918–20), Latvia (1918–20) and Lithuania (1918–19). The Red Army invaded Finland (November 1939); fought the Battles of Khalkhin Gol of May-September 1939 (together with its ally Mongolia) against Japan and its client state Manchukuo; it was deployed when the Soviet Union, in agreement with Nazi Germany, took part in the invasion of Poland in September 1939, and occupied the Baltic States (June 1940), Bessarabia (June–July 1940) and Northern Bukovina (June–July 1940) (from Romania). In World War II the Red Army became a major military force in the defeat of Nazi Germany and conquered Manchuria. After the war, it occupied East Germany and many nations in central and eastern Europe, which became satellite states in the Soviet bloc.
ground_truth: World War II