Question: To which event where three Roman legions were distroyed is the phrase The German Forest sometimes used to refer to?

full_context: Document 1: Legends about Theoderic the Great: The Gothic King Theoderic the Great was remembered in Germanic legend as Dietrich von Bern (Bern is the Middle High German name for Verona, where Theoderic had one of his residences). Dietrich figures in a number of surviving works, and it must be assumed that these draw on long-standing oral tradition. The majority of poems about Dietrich/Theoderic are composed in Middle High German, and are generally divided by modern scholars into historical (German: "historische Dietrichepik") and fantastical (German: either "märchenhafte" or "aventiurehafte Dietrichepik"). The historical poems can loosely be connected with the life of the historical Theoderic and concern his expulsion from Verona by his uncle Ermenrich (Ermanaric) and his attempts to regain his kingdom with the help of Etzel (Attila). The fantastical poems concern his battles with dwarfs, dragons, giants, and other mythical beings, as well as other heroes such as Siegfried. In addition to these two categories of poems, he appears as a supporting character in some poems such as the "Nibelungenlied" and "Biterolf und Dietleib".
Document 2: German Forest: The German Forest (German: "Deutscher Wald" ) was a phrase used both as a metaphor as well as to describe in exaggerated terms an idyllic landscape in German poems, fairy tales and legends of the early 19th century Romantic period. Historical and cultural discourses declared it as the symbol of Germanic-German art and culture, or as in the case of Heinrich Heine or Madame de Staël, as a counter-image of French urbanity. It was also used with reference to historical or legendary events in German forests, such as Tacitus' description of the Battle of the Teutoburg Forest or even the nature mysticism of the stylized Germanic national myth, the "Nibelungenlied" as the history of its multi-faceted reception shows.
Document 3: The Green Snake and the Beautiful Lily: The Green Snake and the Beautiful Lily (German title: "Märchen" or "Das Märchen") is a fairy tale by Johann Wolfgang von Goethe published in 1795 in Friedrich Schiller's German magazine "Die Horen" (The Horae). It concludes Goethe's novella rondo "Conversations of German Emigrants" (1795). "Das Märchen" is regarded as the founding example of the genre of , or artistic fairy tale.
Document 4: Lied: The lied ( or , plural lieder ; ] , plural ] , German for "song") is a setting of a German poem to classical music. The term is used for songs from the late fourteenth or early fifteenth centuries or even to refer to Minnesang from as early as the 12th and 13th centuries. It later came especially to refer to settings of Romantic poetry during the late eighteenth and nineteenth centuries, and into the early twentieth century. Examples include settings by Ludwig van Beethoven, Franz Schubert, Robert Schumann, Johannes Brahms, Hugo Wolf or Richard Strauss. Among English speakers, however, "lied" is often used interchangeably with "art song" to encompass works that the tradition has inspired in other languages. The poems that have been made into lieder often center on pastoral themes or themes of romantic love.
Document 5: Massacre in the Black Forest: Massacre in the Black Forest (German: "Hermann der Cherusker - Die Schlacht im Teutoburger Wald" ) is a 1967 historical drama film set on the northeast frontier of the Roman Empire facing the area of Germania in A.D. 9. The film centers on Hermann, a chieftain of the Cherusci Germanic tribe (in what is now Hesse), who drew three Roman legions into an ambush in the Teutoburg Forest, known as the Battle of the Teutoburg Forest.
Document 6: Gaius Silius: Gaius Silius (died AD 24) was a Roman senator who achieved successes as a general over German barbarians following the disaster of the Battle of the Teutoburg Forest. He had been appointed consul in AD 13. However, Silius became entangled in the aftermath of Sejanus' fall and was forced to commit suicide.
Document 7: Battle of Alesia: The Battle of Alesia or Siege of Alesia was a military engagement in the Gallic Wars that took place in September, 52 BC, around the Gallic "oppidum" (fortified settlement) of Alesia, a major centre of the Mandubii tribe. It was fought by the army of Julius Caesar against a confederation of Gallic tribes united under the leadership of Vercingetorix of the Arverni. It was the last major engagement between Gauls and Romans, and is considered one of Caesar's greatest military achievements and a classic example of siege warfare and investment. The battle of Alesia marked the end of Gallic independence in France and Belgium.
Document 8: The Story of Sigurd the Volsung and the Fall of the Niblungs: The Story of Sigurd the Volsung and the Fall of the Niblungs
Document 9: Publius Quinctilius Varus: Publius Quinctilius Varus (46 BC Cremona, Roman Republic – Sept. 9 AD near Kalkriese, Germany) was a Roman general and politician under the first Roman emperor Augustus. Varus is generally remembered for having lost three Roman legions when ambushed by Germanic tribes led by Arminius in the Battle of the Teutoburg Forest, whereupon he took his own life.
Document 10: Arminius: Arminius (German: "Hermann"; 18/17 BC – AD 21) was a chieftain of the Germanic Cherusci tribe who famously led an allied coalition of Germanic tribes to a decisive victory against three Roman legions in the Battle of the Teutoburg Forest in 9 AD. An auxiliary lieutenant to the Roman general Publius Quinctilius Varus, Arminius used his knowledge of Roman tactics to ambush and destroy the legions.
Document 11: Battle of the Allia: The Battle of the Allia was fought between the Senones (one of the Gallic tribes which had invaded northern Italy) and the Romans. It was fought at the confluence of the rivers Tiber and Allia, eleven Roman miles (16 km) north of Rome. The Romans were routed and subsequently the Senones sacked Rome. The common date given for the battle is 390 BC. This is based on the account of the battle by the Roman historian Livy and the Varronian Chronology, a Roman dating system. The ancient Greek historian Polybius, who used a Greek dating system, derived the date 387/6 BC. Plutarch wrote that the battle took place just after the summer solstice when the moon was near the full, a little more than three hundred and sixty years from the foundation of Rome. That would be shortly after 393 BC. Tacitus said that the battle took place the 15 before the Kalends of August, which is 18 July.
Document 12: Bavarian Forest: The Bavarian Forest (German: "   ") is a wooded low-mountain region in Bavaria, Germany. It extends along the Czech border and is continued on the Czech side by the Šumava (Bohemian Forest). Geographically the Bavarian Forest and Bohemian Forest are sections of the same mountain range. A part of the Bavarian Forest belongs to the Bavarian Forest National Park ("Nationalpark Bayerischer Wald") (240 km²), established in 1970 as the first national park in Germany. Another 3,008 km² belong to the Bavarian Forest Nature Park ("Naturpark Bayerischer Wald"), established 1967, and 1738 km² to the Eastern Bavarian Forest Nature Park ("Naturpark Oberer Bayerischer Wald"), established 1965. The Bavarian Forest is a remnant of the Hercynian Forest that stretched across southern Germania in Roman times. It is the largest protected forest area in central Europe.
Document 13: Arminius (Bruch): Arminius (op. 43) is an oratorio by the German composer Max Bruch. Bruch wrote the work between 1875 and 1877 during the consolidation of the newly founded German Empire. He picked the story revolving around Arminius and the Cherusci-led defeat of three Roman legions in the Teutoburg Forest in 9 A.D., which served as a German national myth from the 16th to the early 20th century.
Document 14: Battle of the Teutoburg Forest: The Battle of the Teutoburg Forest (German: "Schlacht im Teutoburger Wald" , "Hermannsschlacht", or "Varusschlacht"), described as the Varian Disaster ("Clades Variana") by Roman historians, took place in the Teutoburg Forest in 9 CE, when an alliance of Germanic tribes ambushed and decisively destroyed three Roman legions and their auxiliaries, led by Publius Quinctilius Varus. The anti-Roman alliance was led by Arminius, a Germanic officer of Varus' auxilia who had acquired Roman citizenship and had received a Roman military education, thus enabling him to deceive the Roman commander methodically and anticipate the Roman army's tactical responses.
Document 15: Sachsenwald: The Sachsenwald is a forest near Hamburg, Germany. It is an unincorporated area in the amt Hohe Elbgeest. It derives its name (which means 'Saxon wood' in English) from being located in the former Duchy of Saxe-Lauenburg, earlier also called Lower Saxony, now mostly covered by the Herzogtum Lauenburg (Duchy of Lauenburg) district. The Sachsenwald has an area of 68 km. It was given to Otto von Bismarck in 1871 for his achievements for Germany.
ground_truth: Battle of the Teutoburg Forest