Great events do not always have great causes. One of history’s biggest surprises is how sometimes a series of small, seemingly insignificant events can suddenly add up to momentous change.

That’s how it happened with the fall of the Berlin Wall, the point-of-no-return moment in the collapse of the Cold War order. While there were broader historical forces at play, the Wall, a powerful symbol that had separated communist East Berlin from the democratic West for 28 years, would not have opened when and how it did without the last-minute decisions of a secret police officer named Harald Jäger. Struggling with the fear that he was dying of cancer, and angry over insults from higher-ups, he disobeyed direct orders and started letting East Germans through the gate.

Harald Jäger on the Bornholm Bridge, 2014. On November 9, 1989, in defiance of his Communist bosses, he opened the largest checkpoint of the Berlin Wall to let East Germans pass freely to the West. Lambert/ullstein bild/Getty Images

Before telling Jäger’s story, we first have to ask: How did matters get to the point where a single officer of the secret police, or Stasi, could decide the fate of the ugly barrier that had divided Berlin for nearly three decades? After all, it was a confrontation between superpowers that had frozen a dividing line not just across the city, but also across all of Europe since the end of World War II.

In the wake of two catastrophic wars in the first half of the 20th century, the Soviet Union had taken swift action after its WWII victory to turn Central and Eastern Europe into a de facto buffer zone against any future repeat invasion. Residents of the countries between Germany and the Soviet Union were given little choice in the matter as Moscow—which had assembled most of them into a defensive alliance called the Warsaw Pact—came to dominate their political institutions and make all significant political and security decisions. Confrontation with the Western powers soon flared, exacerbated by rising tensions as each side developed and stockpiled thermonuclear weapons. The conflict hardened into the decades-long standoff that came to be known as the Cold War.

In the 1980s, however, the rise of both Ronald Reagan and Mikhail Gorbachev to power brought unexpected changes to U.S,-Soviet relations. Although Reagan initially took a hard-line stance, his personal contacts with Gorbachev, a surprisingly articulate and personable reformer, breathed new life into U.S.-Soviet arms-control negotiations. And Gorbachev himself, seeing the Soviet economy heading for collapse, decided to institute dramatic, liberalizing reforms. In doing so, he opened a window of opportunity, which protesters all over Central and Eastern Europe soon widened. Going far beyond what Gorbachev himself had intended, the Solidarity movement in Poland pushed successfully for a power-sharing regime, and Hungarian leaders began dismantling their country’s barriers to the West.

Aerial photo of the Bornholmer Street border crossing, circa 1985. In this photo, the West is at the top of the image, just over the bridge. The checkpoint itself is the large, walled area in the center of the photo and includes a number of barriers, lights, service buildings and, at left, numbered lanes for processing vehicles. Image courtesy of the author

The leaders of East Germany bucked the trend, however. They were horrified at what Gorbachev was doing and took dramatic steps to try to prevent similar reforms from coming to their half-country. By late 1989, they had sealed the armed borders of East Germany entirely in an effort to prevent their population from fleeing wholesale to the West. Rather than helping to quiet protests, this sealing turned the entire country into a pressure cooker, with massive demonstrations—in Berlin, Leipzig, Dresden and elsewhere—bringing life to a standstill.

The regime launched a belated effort at damage control. At a hastily called press conference on November 9, 1989, Communist party leaders tried to reduce tensions by making it sound as if travel restrictions would soon be liberalized—when in reality travel would remain subject to all manner of fine print. But the official announcing the liberalization botched the messaging so badly that it sounded—unbelievably—as if the ruling regime might just have opened the Wall, effective immediately.

It hadn’t, but the events of that night showed the power of television to change history.

Having seen the press conference on TV, thousands of East Germans flocked to border crossings to see if they could, in fact, pass to the West. Stunned border guards had no idea why they were being inundated, and no orders on how to handle the crowds. Among the many shocked men on duty that night at Bornholmer Street, the biggest checkpoint between East and West Berlin, was Stasi officer Harald Jäger, the senior Stasi officer on duty that historic November night. A deeper dive into his personal history and experiences that evening, based on interviews with Jäger, surviving Stasi documents and television footage from the time, help reveal precisely what he did—and how the Wall opened.

By 1989, Jäger had been a loyal servant of the regime for 25 years. Born in 1943, he had followed in his father’s footsteps and started working on the border at the age of 18, signing up just in time to contribute to the construction of the Berlin Wall. He and his father felt East Germany’s overriding goal should be to avoid another war after the two brutal conflicts that had already occurred that century. To the younger Jäger, the Berlin Wall was a tragic but necessary deterrent to conflict between the states of the Warsaw Pact and the NATO-allied countries in the West.

In 1964, three years after the Wall went up, Harald Jäger secured a position in passport control at the Bornholmer Street checkpoint. Over the next two and a half decades, he ascended to the rank of lieutenant colonel and deputy head of the passport-control unit. Despite the military-sounding title, his post was in many ways a desk job that consisted largely of inspecting travelers’ papers. While he carried a pistol, Jäger had never killed an attempted border crosser. He was essentially a lower-tier record keeper, one of the deputies who reported to more senior Stasi officers. To conceal his identity, he and his colleagues wore uniforms identical to those of the ordinary border guards. But all who worked at the border crossing knew that the official overseeing the passport-control unit on any given day was the senior Stasi officer on duty—and therefore the man in charge.

As a result, the night of November 9 unfolded under Jäger’s supervision as he commanded about a dozen passport-control staff members. He had reported for duty at 8:00 a.m. that morning for an uninterrupted 24-hour shift. Eating dinner in one of the Bornholmer control buildings at about 7:00 p.m., he watched the bungled press conference live, together with some of his men. Unable to restrain himself, he yelled “Bullshit!” at the TV screen, then immediately called his boss, Colonel Rudi Ziegenhorn, the superior officer on duty at the Stasi’s operational command headquarters, to find out what had happened.

Ziegenhorn surprised Jäger by replying that everything remained the same as always, which Jäger found hard to believe. As the crowds swelled, Jäger again called the colonel, who said the troublemakers should be pushed back, as nothing had changed. But, by 8:30 p.m., Jäger’s men estimated the crowd was now well into the hundreds; soon it would be in the thousands.

It was painfully obvious to Jäger that he and the five dozen men guarding the border were outnumbered; their security at that point lay in their weapons. A number of them were carrying pistols, including Jäger, and they also had larger machine guns on-site. Jäger worried increasingly that members of the crowd might try to grab weapons from checkpoint staff.

AUDIO: Fall of the Berlin Wall Audio recording of CBS News on the scene as scores of East Germans climb on top of the once-imprisoning Berlin Wall on the night of November 9, 1989.

He kept calling Ziegenhorn, trying to get some kind of instructions on how to deal with the chaotic situation, but Ziegenhorn replied every time that it was business as usual. Later, Jäger would estimate that he placed about 30 phone calls over the course of the night, all in a mostly fruitless attempt to get new instructions in light of the dramatic developments unfolding in front of him.

Late in the evening, Ziegenhorn decided to add Jäger to a conference call with Ziegenhorn’s own Stasi superiors. Ziegenhorn instructed Jäger to “be quiet” and not let anyone know he was on the line. Unaware that Jäger was listening in, one Stasi superior asked brusquely, “Is this Jäger capable of assessing the situation realistically or is he simply a coward?”

At that, Jäger’s phone connection suddenly cut off. Holding the dead phone in his hand, Jäger felt a wave of anger wash over him. For close to two hours he had been dealing with an unprecedented and threatening situation. He had received no substantive replies to his urgent, repeated requests for guidance. He had been on duty for more than a dozen hours and would be there, at a minimum, all night.

And, if all this chaos weren’t enough, the next day he faced a personal challenge as well: He was displaying the symptoms of cancer, had undergone a battery of tests to confirm the diagnosis, and was scheduled to get the results the next day.

Jäger felt himself reaching his limit. After his 25 years of loyal service at Bornholmer, superiors were questioning his ability to provide an accurate situation report and, worse, suggesting he was a coward. Looking back, Jäger would see that his choices from then on were affected by that moment. A man who had not disobeyed an order in nearly three decades had, with that insult, been pushed too far.

Thousands of celebrants climb atop the Berlin Wall in front of Brandenburg Gate on the night of November 9th, 1989. Crowds had flocked to the border crossings after a botched news announcement spread rapidly that the East German Government would start granting exit visas to anyone who wanted to go to the West. Robert Wallis/Corbis/Getty Images

Suddenly Ziegenhorn called back with one concession: Jäger could let out the biggest troublemakers once and for all, a one-way trip through the Wall with no return. When Jäger started to do so, however, he suddenly had a new problem. Protesters quickly figured out that if you got loud, you got out—and reacted accordingly. Then Jäger learned of yet another problem: Among the first people let out had been young parents. Unlike other protesters, the parents had only wanted to take a quick look in the immediate area just to the west of Bornholmer and then rejoin their young children, who were at home in bed in East Berlin. They had not been told their trip to the West was one-way.

Flush with the heady experience of a swift visit to the West, and a brief look around, they had returned quickly to the western entry of the checkpoint. They happily presented their IDs, saying in merry tones, “Here we are again! We are coming back!” And in response, they heard that they could not go home to their children.

At first they didn’t understand, but soon realized the border guards were serious. The construction of the Wall had, as all Berliners knew, split families without warning. Affected relatives had been forced to wait years to be reunited, if at all, and often were only able to do so with help from officials in Bonn, the provisional capital of West Germany. Now the East German ruling regime threatened to shatter families once again, just as it had done in 1961. Overwhelmed, the parents gave full vent to a powerful mixture of emotions.

Border officials at the western entry, cowed by the intensity of the reaction, called for Jäger to come deal with the anguished parents. When Jäger arrived, he gave in to his own personal anger as well. He had been skeptical of the plan to allow the troublemakers through, and now found he was unwilling to argue with grieving parents on behalf of superior officers who had insulted him.

Jäger snapped. Despite having personally received instructions from Ziegenhorn to prevent anyone who had left from reentering East Germany, he told the young parents that he would make an exception for them. Hearing that, other East Germans standing nearby who also wanted to return asked to be allowed back in as well. Having already taken one step on the path toward disobedience, Jäger felt he might as well take a few more. He instructed the officials at the western entry to let several others return as well. Jäger then returned to the heart of the checkpoint.

The thought crossed his mind that he ought to at least tell Ziegenhorn what he had just done. But then he thought, why bother?

Decades later, he would recall that moment as the key to all that had followed, the end of his loyalty to the regime. From there, it was a slippery slope to the truly major decision of the night: opening the gates entirely. By about a quarter past 11:00 p.m., the crowd on the eastern side of Bornholmer had grown into the tens of thousands, filling all of the approach streets. Loud chants of “Open the gate” erupted regularly. Jäger was facing an uncontrollable sea of thousands of agitated, chanting people. He worried he and his men might soon be in mortal danger.

Surveying the scene, Jäger sensed the time had come to make a fateful decision. He looked at his men and said words to the effect of, Should we shoot all these people or should we open up? Jäger was in charge and did not need their assent, but given the enormity of the choice, he wanted to poll the mood of his men. After looking around, he decided.

Bornholm Bridge on the night of November 9, 1989. Andreas Schoelzel/VISUM/Redux

A little before 11:30 p.m., Jäger phoned his commanding officer with his decision: “I am going to end all controls and let the people out.” Ziegenhorn disagreed, but Jäger no longer cared, and ended the call. His steps down the road of disobedience had taken him to the point where he was willing to ignore his superior entirely.

He began implementing his decision. Jäger’s subordinates Helmut Stöss and Lutz Wasnick received the order to open the main gate, a task that had to be completed by hand. But before they could open it all the way, an enormous crowd started pushing through it from the eastern side. Cheers, jubilation, kisses and tears followed as tens of thousands of people began sweeping through. The massive, unstoppable, joyous crowd poured through the gate and toward the bridge beyond, where even more camera operators filmed the flood of people surging into the West.

The Berlin Wall had opened—but not by force of arms. While the enormous crowd of protesters had loudly and insistently demanded to pass, they had remained peaceful and had not smashed their way through with force, even though Jäger and his men had feared that they might. Thanks to the presence of so many camera crews, the simultaneous collapse of the regime’s control of the Wall and the ultimate moment of peaceful success for the revolution were both caught on film and, soon after, televised.

Jäger had thereby turned the table on his superiors: Now they were the ones surprised by developments at the border. Fortunately, their reactions were belated and confused. Due to the time difference between Berlin and Moscow, it was already in the small hours Soviet time, and apparently no one woke up Gorbachev or his closest advisers. Back in East Germany, the sheer size of the crowds soon overran the ability of the regime to respond. By the time Gorbachev became informed of the situation—which shocked him—it was too late to undo by any other means than massive bloodshed. To his eternal credit, he decided not to go that route.

Thus, a combination of the broader changes in the conduct of the Cold War, the courage of protesters on the street and the last-minute decision of a Stasi officer under almost inconceivable pressure all combined to bring about the unexpected, sudden and peaceful opening of the Berlin Wall. The outcome could have been very different if someone other than Jäger had been on duty that night. Other Stasi officers were anxious to start “spraying bullets,” as they would later recall. And Jäger belatedly learned, when he finally got his medical test results, that he did not in fact have cancer after all, removing one of his main motivations for throwing caution to the wind. He might have been less willing to disobey orders if he hadn’t thought of himself as a dead man walking on the fateful night. But he had—and made history as a result.

AUDIO: West German Foreign Minister on the Fall of Berlin Wall. West German Foreign Minister Hans-Dietrich Genscher traveled to the U.S. to meet with President George H.W. Bush the day after the fall of the Berlin Wall. In his public remarks, Genscher pledges to encourage democratic reform.

Fortunately for Jäger, the collapse of the regime meant that he was never punished, although he did put himself out of work and never again held steady employment. He eventually retired to a small garden cottage near the Polish border, gradually becoming forgotten. But the consequences of his actions, combined with the broader historical forces involved, remain with us today. A combination of great and small causes had, for once, given the history-making night of November 9 a happy ending. It is one of the tragedies of the present day that the peaceful relations between Europe and Russia engendered by the wall’s collapse are once again coming into question.

Mary Elise Sarotte is the Kravis Distinguished Professor of Historical Studies at Johns Hopkins University. She is the author or editor of five books, including 1989: The Struggle to Create Post-Cold War Europe, and The Collapse: The Accidental Opening of the Berlin Wall.

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