On this 75th anniversary of the German invasion of the Soviet Union the Russians will once again remind the world that the Red Army saved European civilisation as well as Russia from the Nazis

Seventy-five years ago Adolf Hitler launched the biggest and most destructive military campaign in history when three million German and allied troops invaded the Soviet Union along a 1,000-mile front.

Operation Barbarossa – the codename for the German invasion of Russia - was no ordinary military campaign: it was an ideological and racist war, a war of destruction and extermination that aimed to kill Jews, enslave the Slavic peoples and destroy communism. The result was a war in which 25 million Soviet citizens died, including a million Jews, executed by the SS in 1941-1942 – an action which became the template for the Nazi Holocaust of European Jewry. European Russia was devastated by the German invasion as 70,000 towns and villages were destroyed along with 98,000 collective farms, tens of thousands of factories and thousands of miles of roads and railways. During the war the USSR lost 15% of its population and 30% of its national wealth.

Instead of a quick victory Germany faced a long war of attrition on the eastern front – a struggle that it was destined to lose now that Soviet Union was allied to Great Britain and the United States

The attack on Russia was the climax of Hitler’s bid to establish Germany as the dominant world power. That bid had begun with the invasion of Poland in September 1939, followed by the German conquest of France in June 1940. By 1941 the German war machine had conquered most of Europe as country after country was invaded or forced to join Hitler’s Axis alliance.

In the west, only Britain, protected by the English Channel and the strength of the Royal Navy and Air Force, remained defiant and undefeated. In the east, the Soviet Union was the last remaining obstacle to German domination of Europe.

The Soviet dictator Joseph Stalin had concluded a non-aggression pact with Hitler in August 1939, together with a secret spheres of influence agreement dividing Poland and the Baltic States between Germany and the Soviet Union. This deal began to unravel in summer 1940 following the defeat of France and Soviet occupation of the Baltic States. In November 1940 Stalin sent his foreign minister, Vyacheslav Molotov, to Berlin to re-negotiate the Nazi-Soviet pact. But Hitler’s offer of a junior partnership in a global coalition against Britain and the United States was rejected by Stalin. Shortly after the Berlin conference Hitler issued the directive for Operation Barbarossa.

The aim of Barbarossa was to conquer Russia in the course of a single Blitzkrieg campaign. Hitler and his generals thought that it would take only a few months to destroy the Red Army, capture Leningrad and Moscow and occupy the western half of the Soviet Union along a line from Archangel to Astrakhan. “The world will hold its breath,” said Hitler as he reassured his generals that all they had to do was kick the door in and the whole rotten structure of the Soviet communist system would collapse.

These ideological prejudices against the Soviet system were reinforced by German perceptions that the Red Army had performed badly in the Winter War with Finland in 1939-1940.

The spur for that war was Finland’s refusal to concede territory the Soviets considered vital to safeguard the security of Leningrad. Moscow expected an easy victory, but the initial Soviet attack on Finland in December 1939 went badly wrong and the Red Army lost tens of thousands of troops. After the Red Army regrouped, a second offensive forced the Finns to accept an unfavourable peace treaty in March 1940.

The German military concluded, wrongly, that the Red Army would be a pushover for the Wehrmacht. What the Germans did not appreciate was that after the Finnish war the Red Army undertook a far-reaching examination of its performance. The result was a series of military reforms, including reinstatement into the armed forces of thousands of “suspect” officers who had been purged by Stalin in the 1930s. So when Hitler attacked the Soviet Union he faced a more experienced and formidable military force than he had imagined.

On the day the invasion began – June 22nd 1941 - Hitler claimed that it was a response to Russian actions and provocations. Nazi propagandists depicted Operation Barbarossa as a pre-emptive strike against an imminent Soviet attack on Germany. By invading Russia Germany was said to be protecting Christian Europe from the Asiatic barbaric hordes in the east.

The myth that Germany fought a defensive war against the Soviet Union persists in ultra-right political circles but there is no evidence that Stalin contemplated starting a war with Germany in summer 1941. On the contrary, Stalin was desperate to avoid war in order to secure as much time as possible to complete Soviet defence preparations. While some Soviet generals were inclined take action to pre-empt the coming German attack that was far too adventurous for Stalin, who feared war, not least because he suspected the British were plotting to realign with Germany and take part in an anti-Bolshevik campaign against the USSR. These suspicions were reinforced by the mysterious flight to Britain of Hitler’s deputy, Rudolph Hess in May 1941, which Stalin interpreted as part of negotiations for an Anglo-German alliance.

By doctrine and tradition the Red Army was offensive-oriented and it was planning to fight an offensive war against Germany but only after Hitler attacked the USSR. Soviet preparations for war revolved around plans for a counter-offensive in which the Red Army would absorb the initial German attack and then launch counter-invasions of enemy territory. There is no evidence that these plans had evolved into a more aggressive strategy by summer 1941. Soviet preparations for war before 22 June 1941 were consistent with a defensive posture.

At first all went well for Hitler as the German armies advanced deep into Soviet territory, destroying everything that was thrown at them and surrounding and capturing millions of enemy troops. As early as July 3, General Franz Halder, chief of the German army general staff, noted in his diary: “On my part it would not be too bold to assert that the campaign against Russia has been won in the space of two weeks.” By September, the Germans had captured Kiev, surrounded Leningrad and were ready to advance on Moscow.

Halder’s triumphalism was a little premature and by early August he was beginning to have doubts: “At the beginning of the war we calculated there would be about 200 enemy divisions against us. But already we have counted 360. If we destroy a dozen, the Russians present us with another dozen.”

But it was not just inexhaustible reserves of manpower that thwarted German plans for a quick and easy victory. Soviet defences did not crumble completely. The Red Army fought back and conducted a tenacious defence once it got over the shock and awe of the initial German attack.

In the Brest fortress on the border with German-occupied Poland, 3,000 Soviet soldiers fought almost to the last man. Odessa, the Soviet Navy’s main port on the Black Sea, held out for weeks against an attack by the Romanian 4th army, while its sister port of Sebastopol fought on for another year. Millions of Soviet soldiers were taken prisoner, but tens of thousands fought their way out of encirclement.

The Red Army did not defend passively; in line with its offensivist ethos it launched numerous counter-attacks, often forcing German forces to retreat and regroup. The Soviet defence of Kiev held up the German advance on eastern Ukraine for nearly a month. So determined was the Soviet defence of Leningrad that Hitler decided to lay siege to the city rather than capture it by frontal assault. In the Smolensk area German and Soviet armies fought for weeks to control the approaches to Moscow.

Hitler’s last chance to defeat the Soviet Union in 1941, and thereby avoid a costly war of attrition, came in the autumn when he attacked Moscow with more than a million men. By the end of November, advance units of the German army could see the spires of Moscow’s Kremlin. But in early December, the Red Army launched a counteroffensive that forced the Germans back 100 miles. For a while Stalin hoped to reverse Operation Barbarossa completely and chase the Germans out of Russia altogether, but that proved beyond the capabilities of the Red Army. Not until the end of 1942, with victory at Stalingrad, did the war turn decisively in the Soviets favour.

Hitler’s inability to capture Moscow signalled the strategic failure of Operation Barbarossa. Instead of a quick victory Germany faced a long war of attrition on the eastern front – a struggle that it was destined to lose now that Soviet Union was allied to Great Britain and the United States.

When Germany invaded Russia, Winston Churchill, the British Prime Minister, immediately declared his solidarity with Soviet Union while US President Roosevelt authorised American aid to the USSR.

The Americans did not enter the conflict officially until the Japanese attack at Pearl Harbor and Hitler’s declaration of war on the United States in December 1941. This seemingly irrational decision by Hitler was not as crazy as it appears in retrospect. By this time the United States was de facto Britain’s ally and was protecting British convoys across the Atlantic, ships laden with American supplies. Crucially, Hitler was still confident of victory on the Eastern Front; the Germany army had stalled in front of Moscow but the full power of the Soviet counter-offensive had yet to be revealed.

Hitler’s decision to declare war on the Americans was also intimately connected to the radicalisation of Nazi policy on the Jewish question. Massacres of Soviet Jews had begun and before the war Hitler had threatened that if there was another global conflict the Jews would all perish. The outbreak of the Pacific War presented Hitler with an opportunity to fulfil his prophecy. The European War was transformed by Hitler into a World War in which the Nazis could pursue their genocidal goals. Shortly after, at Heydrich’s Wansee conference in January 1942, it was decided to round-up Europe’s Jews. Those who were able-bodied would be worked death in the German was economy while the rest would murdered like their religious compatriots in the Soviet Union.

Churchill and Roosevelt both feared the German invasion would succeed. It is important to remember that the initial German successes in Russia were not surprising given a battle-hardened army that had so easily conquered Poland and France. Also working in the German favour was the factor of surprise.

In his so-called secret speech to the 20th congress of the Soviet communist party in 1956 Nikita Khrushchev, Stalin’s successor as party leader, attacked Stalin for allowing the Red Army to be surprised by the German attack – a miscalculation that cost millions of lives and brought the Soviet Union to the brink of defeat, or so it has been argued.

Actually, Stalin was not surprised by the German invasion. It was self-evident that a German attack was coming. What surprised Stalin – and his generals - was the weight and effectiveness of the initial German attack.

Hitler’s attack had been signalled for months by the build-up of German forces along Soviet borders. It is a myth that Stalin’s intelligence officials told the Soviet dictator what he wanted to hear i.e. that Hitler was intent on invading Britain and would not attack the Soviet Union until 1942. For the most part they provided objective reports based on frontier reconnaissance. These reports told the same story as political, diplomatic and espionage sources – that the Germans were preparing to attack the USSR and would do it very soon.

Stalin was well aware the Red Army would suffer some damage if it was not fully mobilised when the Germans chose to attack. The important point to grasp was that Stalin believed that it did not matter if the Red Army was surprised because he expected Soviet defences to hold and to buy enough time for the preparation of counterattacks.

Stalin’s view was perfectly understandable. Three million troops guarded strongly fortified Soviet frontiers. Soviet preparations for war were as extensive as those of the Germans and these defences gave Stalin the confidence to gamble on delaying war with Hitler, even if that meant flying in the face of mounting intelligence of an imminent German attack. Hence, Stalin held back the Red Army’s full mobilisation until the very last moment.

“Mobilisation means war,” Stalin told his chief of staff, General Georgy Zhukov, reminding him that Tsar Nicholas’s mobilisation of the Russian Army during the July Crisis had precipitated war with Germany in 1914.

Stalin’s illusions about the strength of Soviet defences were shared by his generals, who were as shocked as he was by the success of the initial German attack. Zhukov’s efforts to implement plans for counteroffensive action in the days after 22 June made the situation worse by making the Red Army’s forward units even more vulnerable to German encirclement. Most Soviet losses in the early weeks and months of the war were the result of massive encirclement operations by the Germans, such as those at Minsk in June 1941 and Kiev in September 1941.

Importantly, the Red Army had no doctrine or training to deal with encirclement. Soviet soldiers did not know whether to stand and fight or to attempt a break out. It is the failure of military doctrine and preparation which explains the catastrophe that befell the Red Army on 22 June 1941 not the factor of surprise. To be sure, this was Stalin’s failure but it was not his alone. The Soviet generals shared the responsibility – a fact they tried to cover up by blaming Stalin for the disaster.

Eventually, the Red Army learned how to defend effectively, but not before it had suffered astronomical casualties. By the end of 1941 the Red Army had lost nearly 200 divisions in battle and suffered a stunning 4.3 million casualties. The armed force constructed by the Soviets in a decade of mobilisation had all but been destroyed.

The Germans suffered, too, losing nearly a million soldiers by the end of 1941 – casualties far higher than those they had suffered in Poland and France. Because of these losses Barbarossa was the Wehrmacht’s first and last multi-pronged strategic offensive in Russia. When the Wehrmacht resumed the offensive in summer 1942 it was along a single strategic axis – a southern campaign to capture the oil fields at Baku – which supplied 90% of Soviet oil..

It was Hitler’s war for oil that led to the most important battle of the Second World War – the fight for Stalingrad in the autumn of 1942. Defeat at Stalingrad was the point of no return for the Wehrmacht. With the encirclement and destruction of the 6th army in Stalingrad the Red Army seized the strategic initiative and thereafter inflicted defeat after defeat on the Germans all the way to the capture of Berlin by Zhukov in May 1945.

On this 75th anniversary of the German invasion of the Soviet Union the Russians will once again remind the world that the Red Army saved European civilisation as well as Russia from the Nazis. True, the Soviets did not win the war on their own, but in alliance with Britain, the US and other allies. As the old saying goes, the British gave time, the Americans gave money and the Soviets gave their blood to defeat Hitler. But, as Churchill said, it was the Red Army which tore the guts out of Hitler’s war machine.

During the war the Red Army destroyed 600 enemy divisions – Finnish, Rumanian, Hungarian, Spanish and Italian as well as German. Among the Axis losses were 48,000 tanks, 167,000 artillery pieces and 77,000 aircraft. Germany incurred 10 million military casualties including three million dead on the Eastern Front. This represented 75% of Germany’s total losses during the Second World War.

After the war surviving German generals claimed they had lost to the Red Army because it had more troops and resources and was better adapted to the weather and terrain of Russia. Hitler was also a convenient scapegoat for Nazi Germany’s defeat by a supposedly barbarian and backward nation. His generals declared Hitler to be a poor supreme commander whose strategic errors had snatched defeat from the jaws of victory. Conveniently, these same generals forgot the bad advice they gave to Hitler. In relation to the Wehrmacht’s role in the Holocaust they were even more forgetful.

In truth, the German-led forces lost to an army that was better as well a bigger: an army with superior arms, strategy and leadership. Stalin was a far better Supreme Commander than Hitler. The Soviet dictator did not seek to dominate his generals. He did not always take their advice but he learned from their military professionalism and strove to create a coherent and effective high command.

Stalin made as many mistakes as Hitler but he learned from them as did the Red Army as a whole. During the war the Red Army developed into a highly effective learning organisation. The experience and lessons of combat and command were assiduously collected, analysed and disseminated. The Soviets kept command structures, force organisation and military doctrine under constant review. Meanwhile, military technology improved steadily and the Soviets made good use of the thousands of tanks, planes and trucks supplied by their western allies.

It is sometimes said that the Soviet victory over Nazi Germany was pyrrhic — a victory won at too great a cost. But much worse would have been the alternative of a triumphant Nazi empire in Europe that would have destroyed western democracy as well as Soviet socialism and completed Hitler’s genocide of the Jews.

Geoffrey Roberts is Professor of History at University College Cork, Ireland. He is the author of Stalin's Wars: From World War to Cold War (2008) and Stalin’s General: The Life of Georgy Zhukov (2012)