On the night of April 3, 1919, President Woodrow Wilson began to suffer from a violent cough. His condition quickly worsened to the point that his personal doctor, Cary Grayson, thought the president might have been poisoned. Grayson later described the long night spent at Wilson鈥檚 bedside as 鈥渙ne of the worst through which I have ever passed. I was able to control the spasms of coughing but his condition looked very serious.鈥

The culprit wasn鈥檛 poison, but the same potent strain of influenza nicknamed the 鈥Spanish flu鈥 that would eventually kill an estimated 20 million worldwide, including more than 600,000 in the United States. Wilson鈥檚 illness was made even worse by its timing鈥攖he president was left bedridden in the middle of the most important negotiations of his life, the Paris Peace Conference to end World War I.

Before the Flu, a Deadlock

Wilson came to the Paris negotiations armed with his visionary 鈥14 Points鈥 strategy for achieving world peace. It included calls for open and transparent peace treaties, freedom and self-determination for all European nations, disarmament, and above all the creation of a 鈥済eneral association of nations鈥濃攍ater called the League of Nations鈥攖o actively prevent all future wars.

But parts of Wilson鈥檚 post-war scheme were adamantly opposed by the other chief powers at the Paris Peace Conference, namely France and Great Britain. The French prime minister, Georges Clemenceau, openly clashed with Wilson over the level of economic punishment to inflict on the Germans. Clemenceau demanded billions in reparations for the monumental loss of French lives and property at German hands, but Wilson wanted to spare Germany such humiliation and focus instead on building up the League of Nations.

By April, the Paris negotiations were deadlocked, and that was precisely the moment when Wilson fell ill. The president was confined to his bed for five days battling a 103-degree fever and racking coughs while his doctor, Grayson, lied to the press that it was nothing more than a bad cold.

READ MORE: US Presidents Who Became Ill in Office

Post-Flu Neurological Disorders 

WATCH: The Spanish Flu Was Deadlier than WWI

The 1918 鈥淪panish鈥 flu was notorious for aggressively attacking the respiratory system. The infection was worst in the young and previously healthy, whose immune systems could overreact to the virus and drown the lungs with fluid, killing patients in a matter of days. But for those who survived the initial onslaught, some also experienced neurological symptoms.

Even after their burning fevers subsided, flu victims described 鈥減ost-influenzal manifestations,鈥 psychotic delusions and visions that resulted from damage to the nervous system, says John Barry, author of .

鈥淭he most comprehensive study of the 1918 pandemic noted how common neurological disorders were,鈥 says Barry. 鈥淭hey were second only to the lung. This included psychosis, which was usually temporary.鈥

From numerous sources, it appears that Wilson suffered from similar effects during his fight with the flu at the Paris Peace Conference.

鈥淗e became paranoid,鈥 says Barry. 鈥淲ilson thought the French had spies all around him. He was bizarrely obsessed with his furniture and his automobiles, and pretty much everyone around him noted it.鈥

Wilson鈥檚 chief usher, a man named Irwin Hoover, wrote later that 鈥渟omething queer was happening in [the president鈥檚] mind鈥 and that 鈥淸o]ne thing is certain: he was never the same after this little spell of sickness.鈥

The British prime minister, Lloyd George, came to visit Wilson during his recuperation at the H么tel du Prince Murat and labeled Wilson鈥檚 condition a 鈥渘ervous and spiritual breakdown鈥 in the middle of the heated Paris negotiations.

Although instances of 鈥溾 had been reported by physicians as early as the Russian Flu outbreak of 1889, there was no treatment for the condition, which usually went away on its own. One hypothesis is that the neurological disorder experienced by Wilson and others was caused by brain swelling (encephalitis) associated with the flu. 

Wilson Capitulates in Paris

Mansell/The LIFE Picture Collection/Getty Images
Georges Clemenceau, President Woodrow Wilson and British Prime Minister David Lloyd George during the Paris Peace Conference on June 28, 1919.

When Wilson was finally well enough to re-join the Conference, he scarcely resembled the man who had fought so doggedly for his principles. The flu had weakened both his body and his mind, and Wilson simply didn鈥檛 have the strength or the will to stand his ground.

鈥淭he impact was pretty dramatic in my view,鈥 says Barry. 鈥淲ilson had been adamant, insisting on the 鈥14 Points,鈥 self-determination, and 鈥榩eace without victory.鈥 Clemenceau had even accused him of being 鈥榩ro-German.鈥 All of a sudden, Wilson caved in on all 14 points except the League of Nations, and only because Clemenceau threw him a bone.鈥

For Wilson鈥檚 negotiation team in Paris and his supporters back home, the Treaty of Versailles signed in June 1919 was a betrayal of everything Wilson had stood for, and set the stage for more conflict and death on European soil.

William Bullitt, an assistant to the Department of State and a loyal Wilson attach茅 at the Paris negotiations, immediately proffered his resignation.

鈥淚 was one of the millions who trusted confidently and implicitly in your leadership and believed that you would take nothing less than 鈥榓 permanent peace鈥 based on 鈥榰nselfish and unbiased justice,鈥欌 wrote Bullitt. 鈥淏ut our government has consented now to deliver the suffering peoples of the world to new oppressions, subjections, dismemberments鈥攁 new century of war.鈥

READ MORE: Germany's World War I Debt Was So Crushing It Took 92 Years to Pay Off

Most of Wilson's '14 Points' Are Abandoned 

The young aide鈥檚 assessment was tragically prescient. Historians agree that one of the chief causes of the rise of Adolf Hitler鈥檚 Nazi party was the humiliation and economic desperation inflicted on the German people by the Treaty of Versailles. Instead of safeguarding the world from future wars, the Treaty of Versailles helped pave the road to World War II.

Did Wilson鈥檚 illness play a significant and disruptive role in the Paris peace negotiations? Barry said it certainly had an impact.

鈥淵ou can鈥檛 absolutely prove that he wouldn't have caved in on everything anyway, but if you know anything about Wilson, there鈥檚 nothing in his behavior that suggests he was a compromiser on issues like that,鈥 says Barry. 鈥淨uite the reverse. He was insistent that it was 鈥榟is way or the highway鈥 on pretty much everything.鈥

Returning to the United States, things only got worse for Wilson. First, Congress rejected American participation in the League of Nations, the last surviving remnant of the 鈥14 Points,鈥 and then Wilson suffered a debilitating stroke from which he never fully recovered. 

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