22 June 1941: On this day in history, Nazi Germany launched Operation Barbarossa, the invasion of the Soviet Union. With a force of over 3 million, it is widely recognised as the largest invasion in military history.

After stunning successes in western Europe, Hitler was certain that victory over his ideological enemy to the east would be swift and decisive. Spurred on by this misguided belief, the German military was completely unprepared for what they would encounter on their advance. An unfathomably vast land, a tenacious and seemingly unlimited opposing force and brutal winters would ensure Stalin’s Red Army eventually gained the upper hand. Despite the failure of the German offensive, the invading forces would inflict untold misery on the Soviet population during a horrific wave of violence which, 80 years later, the world is still coming to terms with.

The invasion of the Soviet Union had long been central to Hitler’s vision. He had raved about the need for Lebensraum, or living space for the German “Volk” since his days as a rabble-rousing upstart in the beer halls of Munich. This desire was clear to any who had read his book Mein Kampf, published in 1924. For Soviet leader Joseph Stalin, Operation Barbarossa should have come as no surprise. Nevertheless, despite continued warnings – not only from British Prime Minister Winston Churchill but also from Soviet diplomats and spies – it seems that the Soviet leader was caught off guard. Although many aside from Stalin saw the Nazi offensive coming, no one was prepared for what followed.

The eastern European theatre of World War Two was not merely a war of expansion, this was a war of extermination. Following the German front line were SS Einsatzgruppen, mobile killing squads, whose task it was to round up the civilian population and murder anybody deemed undesirable by Nazi ideology. These mass shootings, such as that of Babi Yar outside Kiev in which 30,000 people were shot in just two days, would claim the lives of around 2 million innocent people, including 1.3 million Jews. As the war progressed, new more efficient forms of mass murder would arise in the form of industrial killing centres like Auschwitz and Treblinka. It was here in the east where the depravity of Nazi ideology would reach its full and horrifying extent.

“Kick in the door and the whole rotten structure will come crashing down” this sentiment was repeated like a mantra by Nazi leadership during the planning stages of their eastern offensive. In practise, this couldn’t have been further from the truth. The “Great Patriotic War” as it’s still known in the former Soviet states, galvanised a vast and fragmented population, arousing a fierce nationalism which would spur their soldiers on all the way to Berlin. The atrocities committed against their country folk, the evidence of which was clearly seen during the Red Army’s advance towards Europe, only heightened the soldiers’ lust for revenge.

Operation Barbarossa is recognised as the definitive turning point of World War Two, perhaps only matched by Japan’s attack on Pearl Harbour later that year, which would ultimately tip the balance against the Axis powers. By bringing the Soviet Union into the war, Adolf Hitler had unknowingly sealed his fate as well as that of his so-called Third Reich. Today, we remember the date not only in terms of a large-scale military offensive, but as a turning point in human history. The massacre of Jews, Sinti and Roma, Slavs, Homosexuals and many more in the gas chambers, ghettos and killing fields of eastern Europe, prove the importance of combating the vilification and dehumanisation of certain groups of people. A lesson which, 80 years on, is as relevant as ever.

This edition of On This Day in Berlin History was written by Berlin Guides Association member, Chris Cooke. It’s one of four noteworthy events he’s chosen to remember this summer. Keep an eye on our blog to see what else made the cut.