For years after Adolf Hitler’s rise to power, the only thing that united Nazi Germany and the Soviet Union was their mutual hatred. That all changed when the mortal enemies cast aside their vast ideological differences and signed a stunning diplomatic pledge of nonaggression that cleared the way for the start of World War II.

On the night of August 20, 1939, German Chancellor Adolf Hitler reached out to a bitter foe with a desperate plea. Time was running short on preparations for his planned invasion of Poland on September 1, and Hitler needed the Soviet Union to stay out of his war. In a telegrammed letter rushed to Joseph Stalin, Hitler asked the Soviet dictator to arrange for a meeting between German foreign minister Joachim von Ribbentrop and his Soviet counterpart, Vyacheslav Molotov, as soon as possible. For months, the USSR had been in negotiations with Britain and France, who had pledged to defend Poland if Germany invaded, to form a three-way alliance against Nazi aggression. Germany and the USSR, however, had signed an economic agreement the day before. Now Hitler wanted a political pact as well, an idea Molotov said he “warmly welcomed.” With battle preparation plans on hold as the European powers considered forming a united front against Germany, Hitler could not hide his urgency. “The tension between Germany and Poland has become intolerable,” he warned Stalin. “A crisis may arise any day.”

Stalin’s response finally arrived 27 hours later: Send Ribbentrop to Moscow.

On August 23, 1939, Ribbentrop arrived with written orders in hand from Hitler to make the deal. Such a diplomatic foray would have been unthinkable only months before. The Nazis and Soviets had been mortal enemies on the opposite sides of the ideological spectrum who used hatred of one another to fuel their political purges and murderous regimes. Now, however, Realpolitik trumped ideology. After the Germans occupied Czechoslovakia earlier in the year in violation of the Munich Agreement, Stalin questioned the resolve of the British and French to fight the Nazis. The Soviets, meanwhile, found a peace deal with the Germans attractive given that they were already engaged in a fierce battle on their eastern front with the Japanese and the Red Army was still weakened from Stalin’s purge of its top commanders in 1937 and 1938.

Stalin and Ribbentrop at signing of nonaggression pact
Stalin and Ribbentrop at signing of nonaggression pact

So sudden was the thaw between the strange bedfellows that the five swastika flags rushed to the airport to greet Ribbentrop upon his arrival had to be taken from Soviet movie studios producing anti-Nazi propaganda films. Once seated at the negotiating table inside the Kremlin, the German foreign minister proposed a lofty preamble about the countries’ warm relations, but even a totalitarian dictator knew that the truth could only be bent to a certain degree before it snapped. “The Soviet government could not suddenly present to the public assurances of friendship after they had been covered with pails of manure by the Nazi government for six years,” Stalin said, according to William Shirer’s “The Rise and Fall of the Third Reich.”

While Soviet negotiations with the British and French had dragged on for months, it took mere hours to hammer out a deal with the Germans. The meeting “began and ended briskly, just to show how businesslike these dictators are,” the New York Times editorialized. Officially called the Molotov-Ribbentrop Pact but also known as the Hitler-Stalin Pact, the nonaggression agreement was simple and straightforward. Both countries pledged for 10 years “to desist from any act of violence, any aggressive action and any attack on each other, either individually or jointly with other powers.”

As a large framed photograph of Vladimir Lenin gazed down sternly upon the smoke-filled room, Ribbentrop and Molotov affixed their signatures to the agreement. A smiling Stalin was as bubbly as the Crimean sparkling wine that he raised in a spontaneous toast to Hitler. “I know how much the German nation loves its Fuhrer,” he said. “I should therefore like to drink to his heath.”

The agreement took effect the moment pen touched paper, an unusual diplomatic clause that reflected just how rushed Hitler felt. Ribbentrop phoned an anxious Hitler at his mountain retreat in Bavaria with the news. “That will hit like a bombshell,” said an ecstatic Hitler, who could now invade Poland without fear of a Soviet intervention and a two-front war that had doomed German in World War I.

British press reacts to news of the pact (Credit: Bettman/Corbis)
British press reacts to news of the pact (Credit: Bettman/Corbis)

“The sinister news broke upon the world like an explosion,” Winston Churchill later wrote. And that was just the news the world knew about, for in addition to the non-aggression pact, the Nazis and Soviets entered into a secret protocol that only came to light after the conclusion of World War II. The two countries took a carving knife to Poland with the Germans taking the larger western slice. The Soviets were given a free hand in Bessarabia in southeast Europe and the Baltic states of Estonia, Latvia and Finland, while Lithuania fell into the German sphere of influence.

Before Ribbentrop left the Kremlin, Stalin pulled him aside. “The Soviet Government take the new pact very seriously,” the dictator said, and he could guarantee on his “word of honor that the Soviet Union would not betray its partner.” Stalin must have wondered if Hitler felt the same, given the chancellor’s willingness to agree to all Soviet demands as well as his serial habit of breaking treaties.

“Our pact means that the greatest European powers have agreed to eliminate the threat of war and to live in peace,” Molotov told the Supreme Soviet before it unanimously ratified the pact on the evening of August 31. Hours later, more than a million German troops crossed the border with Poland. World War II had begun. Within weeks, the Soviets occupied eastern Poland under the guise of protecting its residents from the Germans. Months later, Stalin’s troops marched into the Baltics and Bessarabia.

Before the signing of the non-aggression pact, President Franklin D. Roosevelt warned Stalin that “it was as certain as that the night followed the day that as soon as Hitler had conquered France he would turn on Russia and it would be the Soviets’ turn next.” The words proved prescient when on June 22, 1941, Hitler unilaterally broke his deal with Stalin and launched the largest surprise attack in the history of warfare.