Where there’s smoke, there’s fire, and where there’s fire, conspiracy theories are sure to follow. At least, that’s what happened in Germany on February 27, 1933, when a sizeable portion of the parliamentary building in Berlin, the Reichstag, went up in flames from an arson attack.

It was the canary in the political coal mine—a flashpoint event when Adolf Hitler played upon public and political fears to consolidate power, setting the stage for the rise of Nazi Germany. Since then, it’s become a powerful political metaphor. Whenever citizens and politicians feel threatened by executive overreach, the “Reichstag Fire” is referenced as a cautionary tale.

Whether it’s a congressman referencing the fire to question President George W. Bush, a comparison of President Barack Obama to Adolf Hitler, or numerous pundits invoking the incident to foment fear over President Donald Trump’s next potential executive order, the German arson is an irrepressible political motif. It’s become a kind of political shorthand—a reference so familiar that New York Times columnist Paul Krugman only had to use the word “fire” in the headline of an inflammatory column about the Trump administration to call up images of national chaos and power grabs. But the true story of the climactic event is far more complicated than the headlines suggest.

Germany’s first experiment with liberal democracy was born of the 1919 Weimar Constitution, established after the conclusion of World War I. It called for a president elected by direct ballot, who would appoint a chancellor to introduce legislation to members of the Reichstag (who were also elected by popular vote). The president retained the power to dismiss his cabinet and the chancellor, dissolve an ineffective Reichstag, and, in cases of national emergency, invoke something known as Article 48, which gave the president dictatorial powers and the right to intervene directly in the governance of Germany’s 19 territorial states.

Following a stint in jail for his failed Beer Hall Putsch in 1923, Hitler poured his energy into attaining power through legal channels. He rose to the head of the National Socialist German Workers’ Party (Nazis), and by 1928 the group’s membership exceeded 100,000. The Nazis denounced the Weimar Republic and the “November criminals,” politicians had signed the Treaty of Versailles. The treaty forced Germany to accept responsibility for World War I, pay huge remunerations, transfer territory to their neighbors and limit the size of the military.

Despite its considerable growth, the Nazi party won only 2.6 percent of the vote in the 1928 election. But then the Great Depression hit, sending the U.S. and Europe into an economic tailspin and shooting the number of unemployed up to 6 million people in Germany (around 30 percent of the population). The sudden slump caused massive social upheaval, which the Nazis exploited to gain further political traction. By 1930, the Nazis won 18.3 percent of the Reichstag vote and became the second largest party after the Social Democrats, while the Communist party also grew to ten percent of the vote.

The economic unrest of the early 1930s meant that no single political party had a majority in the Reichstag, so fragile coalitions held the nation together. Faced with political chaos, President Paul von Hindenburg dissolved the Reichstag again and again. Frequent elections followed.

The Nazis aligned with other right-leaning factions and gradually worked their way up to 33 percent of the vote—but were unable to reach a full majority. In January 1933, Hindenburg reluctantly appointed Hitler as chancellor on the advice of Franz von Papen, a disgruntled former chancellor who believed the conservative bourgeois parties should ally with the Nazis to keep the Communists out of power. March 5 was set as the date for another series of Reichstag elections in hopes that one party might finally achieve the majority.

Meanwhile, the Nazis seized even more power, infiltrating the police and empowering ordinary party members as law enforcement officers. On February 22, Hitler used his powers as chancellor to enroll 50,000 Nazi SA men (also known as stormtroopers) as auxiliary police. Two days later, Hermann Göring, Minister of the Interior and one of Hitler’s closest compatriots, ordered a raid on Communist headquarters. Following the raid, the Nazis announced (falsely) that they’d found evidence of seditious material. They claimed the Communists were planning to attack public buildings.

On the night of February 27, around 9:00, pedestrians near the Reichstag heard the sound of breaking glass. Soon after, flames erupted from the building. It took fire engines hours to quell the fire, which destroyed the debating chamber and the Reichstag’s gilded cupola, ultimately causing over $1 million in damage. Police arrested an unemployed Dutch construction worker named Marinus van der Lubbe on the scene. The young man was found outside the building with firelighters in his possession and was panting and sweaty.

“This is a God-given signal,” Hitler told von Papen when they arrived on the scene. “If this fire, as I believe, is the work of the Communists, then we must crush out this murderous pest with an iron fist.”

A few hours later, on February 28, Hindenburg invoked Article 48 and the cabinet drew up the “Decree of the Reich President for the Protection of the People and State.” The act abolished freedom of speech, assembly, privacy and the press; legalized phone tapping and interception of correspondence; and suspended the autonomy of federated states, like Bavaria. That night around 4,000 people were arrested, imprisoned and tortured by the SA. Although the Communist party had won 17 percent of the Reichstag elections in November 1932, and the German people elected 81 Communist deputies in the March 5 elections, many were detained indefinitely after the fire. Their empty seats left the Nazis largely free to do as they wished.

Later that year, a sensational criminal trial got under way. The accused included van der Lubbe, Ernst Torgler (leader of the Communist Party in the Reichstag) and three Bulgarian Communists.

As the trial in Germany proceeded, a different kind of trial captured the public discourse. Willi Münzenberg, a German Communist, allied himself with other Communists to undertake an independent investigation of the fire. The combined research resulted in the publication of The Brown Book on the Reichstag Fire and Hitler Terror. It included early accounts of Nazi brutality, as well as an argument that van der Lubbe was a pawn of the Nazis. Hitler’s party members were the real criminals, the book argued, and they orchestrated the fire to consolidate political power. The book became a bestseller, translated into 24 languages and sold around Europe and the U.S.

“Behind the controversy stood the larger issue of the nature of the National Socialist seizure of power: was the dictatorship the result of a political crime or simply an opportune event?” writes historian Anson Rabinbach.

It’s a question that scholars and historians have been debating since the fire erupted. Their arguments fill hundreds of pages and numerous books. Some denounce the other side’s evidence as fabricated while others dig their heels in deeper.

For historian Peter Black, a consultant for the United States Holocaust Memorial Museum, the one-man theory of van der Lubbe acting alone seemed correct until 2013, when new research came out with Benjamin Hett’s book, Burning the Reichstag. Hett wrote that, given the extent of the fire and the amount of time that would have been needed inside the Reichstag to set it, there was no way that van der Lubbe acted alone. Citing witness testimonies that became available after the fall of the Soviet Union, Hett argued that the Communists weren’t involved at all; rather, said Hett, the group of Nazis who investigated the fire and later discussed its causes with historians covered up Nazi involvement to evade war crimes prosecution.

Black does not entirely agree with Hett’s assessment, but he says that he is now convinced the one-man theory is false. “I would say that van der Lubbe could not have started that fire alone, based on the evidence that is now available,” he says. “It seems likely that the Nazis were involved. But you don’t have anyone who can say, yes, I saw the Nazis.”

Whether or not he had help from the Nazis, van der Lubbe confessed to the arson, was found guilty and sentenced to death. The four other defendants were acquitted due to lack of evidence, but the fire continued to be brandished as a Communist plot.

On March 23, the Reichstag passed the Enabling Act, the partner piece of legislation to the February 28 Decree for the Protection of People and State. The Enabling Act assigned all legislative power to Hitler and his ministers, thus securing their ability to control the political apparatus. When President Hindenburg died in August 1934, Hitler wrote a new law that combined the offices of president and chancellor. It was sanctioned by a national plebiscite.

Did the Nazis really assist in setting the fire? Did van der Lubbe act alone? It’s almost impossible to know, since “most of the people who would be in the know either didn’t survive WWII or weren’t willing to talk about it afterwards,” Black says. The German government exonerated van der Lubbe in 2008, a full 75 years after he was beheaded. And though the Reichstag fire kindled decades of mystery, one thing is clear: It played a critical role in the Nazi’s rise to power. The fire proved the sway of Germany’s dangerous new dictator—whose vision to remake the nation had only just begun.