One pact, two dictators

Just one week after the signing of the Molotov-Ribbentrop Pact (officially the Treaty of Non-Aggression between Germany and the Union of Soviet Socialist Republics) on August 23, 1939, the Second World War began with the invasion of Poland by Nazi Germany. Two weeks later, following the terms of the pact, Soviet troops also invaded Poland.

The two sides celebrated their victory with a "brotherhood" parade of Red Army and Wehrmacht units who marched arm-in-arm through the occupied town of Brest, watched over by Soviet Brigade Commander Semyon Krivoshein and German General Heinz Guderian, who stood side by side.

Two years later, Guderian's tank units were at Moscow's doorstep. The short "honeymoon" between the two countries was over.

Stalin's calculations

A secret protocol between the countries not only foresaw the division of Poland but also sealed the fate of the Baltic states, giving the Soviet Union the go-ahead to invade and annex them. The Soviets also annexed Romania's provinces of Bessarabia (today's Moldova) and northern Bukovina (now in Ukraine) and the Czechoslovak territory of Carpathian Ruthenia (also now in Ukraine).

The pact also declared Finland to be within the Soviet sphere of influence, and the USSR promptly invaded, though its forces were initially driven back by the Finns in the Winter War. The Soviets eventually took Karelia and other territories from Finland.

On September 28, 1939, a further protocol delineating those new boundaries was signed, as surprising to the citizens of the Soviet Union and Third Reich as it was to the rest of the world. In truth, Stalin and Hitler had been preparing their alliance since 1938. Hitler in particular was in a hurry: he wanted to begin the campaign against Poland before the autumn rains.

Hitler's goal in signing the pacts was clear - that much German and Russian historians can agree upon. Stalin's motivations, however, remain disputed.

"In the summer of 1939, Stalin had the largest land army in the world," well-known Russian historian Mark Solonin said in an interview with DW. "He could have made it clear to Hitler that if he invaded Poland, millions of Soviet soldiers would arrive the next day at Poland's border. There wouldn't have been war then. But Stalin didn't want to disrupt Hitler."

German historian Jörg Ganzenmüller sees strategic thinking in the Soviet leader's actions. "Stalin knew that, sooner or later, Hitler would attack the Soviet Union. He was familiar with Hitler's 'Lebensraum' concept. His calculation was: if Germany's entangled in a war with the Western powers, then Hitler wouldn't wager a two-front war. In the meantime, the Soviet Union could continue rearming."

Stalin, he added, was always worried the capitalist powers would unite and together invade the Soviet Union. That's why it was his goal to unleash a war between these powers.

"This war was, for Stalin, the security guarantee, and not at all the pact itself."

About-face in Moscow

After the signing of the pact between the two countries' foreign ministers in Moscow, Stalin raised a glass to the health of the "Führer." Soviet Foreign Minister Vyacheslav Molotov praised Hitler's "peaceful intentions" at a meeting of the Supreme Soviet, the country's highest legislative body. He called the now-ongoing war by the Western allies against Hitler "senseless and criminal." Later, in Berlin, he was received warmly by Hitler, senior military official Hermann Göring and Deputy Führer Rudolf Hess.

During the 22 months the alliance held, the Soviet press no longer attacked Nazi policies. Anti-fascist films were banned from cinemas. Theaters no longer performed dramas with anti-Nazi content. Just before the pact was signed, Maxim Litvinov, the Soviet people's comissar for foreign affairs and himself a Jew, was dismissed. He had advocated an alliance with Western democracies and no longer fit within Moscow's new strategy.

Secret police and economic ties

For both regimes, the pact was advantageous beyond the political realm. Between August 1939 and June 22, 1941, Moscow delivered petroleum products, grain, nickel, manganese and chromium for steel production, phosphate, wood and other materials.

In return, the Third Reich delivered fighter jets, explosive chemicals and bombs, radio stations, industrial facilities and even the cruiser Lützow, which the Soviets renamed Petropavlovsk. In addition, the Soviet Union received a loan of 200 million reichsmarks.

"The most important element in German-Soviet cooperation between 1939 and 1941 wasn't the cooperation between the armies at all, but rather the economic deliveries on a large scale that resulted," Ganzenmüller said.

"There are reports, even from June 22, 1941 - the day the Wehrmacht invaded the Soviet Union - that the soldiers encountered trains with Soviet deliveries. The Soviets were true to the contract until the end."

Another "partnership" existed between the NKVD - the Soviet secret police - and its German counterpart, the Gestapo. A secret agreement approved by the Soviet leadership gave anti-fascist Germans and Austrians who had fought against Hitler to the Gestapo. Many dozens of them, including well-known German communist Margarete Buber-Neumann, were handed over. The majority were murdered.

Stalin's miscalculation

"Stalin lost," Solonin said. "He misjudged the ratios of force. He thought, here comes a long-term slaughter, similar to Verdun in World War I. But by May 1940, or at least by June, France had been crushed. Hitler controlled the largest part of continental Europe. Stalin's plan - to arrive later as the supreme judge over the burned cities of a shattered and bloodied Europe - was off-target."

Ganzenmüller agrees. "Stalin really believed until the end - until June 22, 1941 - that Germany wouldn't conduct a two-front war. That this strategy didn't pan out was a surprise and a disappointment for him. For three weeks after the war began, he didn't make a single public appearance. He was as if paralyzed. His plan fell apart like a house of cards."