Was the rise of Nazism a side effect of the 1918 flu pandemic?

In the spring of 1919, four men met 175 times in Paris, and decided the destiny of the world.

The prime ministers of France (Georges Clemenceau), Italy (Vittorio Emanuele Orlando), Britain (David Lloyd George), and US president Woodrow Wilson discussed the Treaty of Versailles, which established the official end of World War I and the peace conditions to follow.

Germany was declared responsible for the war and asked to pay—on top of disarmament and relinquishing 10% of its territory—crushing reparations. In his 1919 book, The Economic Consequences of the Peace, British economist John Maynard Keynes predicted that those reparations would lead to the collapse of the country, with consequences that would reverberate over Europe for years go come. Many historians agree that’s exactly what happened: The level of sacrifice imposed on German citizens created fertile grounds for far-right, nationalistic doctrines, leading to the rise of Nazism.

But the treaty wasn’t always going to be so tough on Germany, and it might have not caused such devastating effects—had it not been for the influenza pandemic.

“His weakness of body naturally reacted upon his mind.”

Wilson, who had been publicly dismissive of the gravity of the 1918-1919 pandemic, contracted the flu in the spring of 1919, soon after he arrived in Paris for the negotiations. His staff downplayed the illness, saying he caught a cold due to the bad weather, but he was actually very sick, and the flu was debilitating.

On April 3, 1919, as the negotiations moved away from the compromise Wilson wanted and toward harsher punishment for Germany, the US president was on the verge of walking out of the talks, writes Susan Kent, the author of The Influenza Pandemic of 1918-1919. But he was struck with a fever so high that he was unable to do so, and remained in Paris, bedridden for the following days.

Within days, the parties reached an agreement, which was all but a defeat for Wilson. The US was able to soften some aspects of the treaty, but essentially none of Wilson’s initial positions made it to the final version of the agreement.

The reason, those close to Wilson believe, is that he was too weak. “One thing was certain: [H]e was never the same after this little spell of sickness,” said Irvin Hoover, a close collaborator at the time. Like many flu survivors, the president experienced confusion, depression, and mental fatigue. “[H]e never did regain his physical strength, and his weakness of body naturally reacted upon his mind. He lacked his old quickness of grasp,” said the president’s secret service agent.

Lacking the energy, the intellectual capacity, and even the interest to continue his battle with Lloyd George and Clemenceau, he simply gave in, and assented to a peace so unjust that, he told an aide in early May, “if I were a German, I think I should not sign it.”