It wasn’t that long ago that people believed mental illness behaved like the common cold. One of the reasons for the establishment of mental asylums was to quarantine the insane, thus protecting everyone else from the malady that afflicted their minds.

In our enlightened age, we scoff at such primitive notions. Even so, there are some situations where you can’t help but wonder if there isn’t a grain of truth in the quaint superstition. Consider, for example, one of the most infamous acts in history: the assassination of Abraham Lincoln.

On April 14, 1865, President and Mrs. Lincoln attended Ford’s Theater to see Our American Cousin. They were joined by Major Henry Rathbone and his fiancée, Clara Harris. At 10:14 pm, John Wilkes Booth entered the presidential box and shot the president in the back of the head.

The assassination was, itself, an act of insanity, but is it too much of a stretch to claim that it was a contagion?

Abraham Lincoln and Mary Todd Lincoln

The love between the Lincolns was undeniable, but their marriage was troubled. They had four children, but only one survived to adulthood. Abraham struggled with depression for much of his life. This was aggravated by the precarious state of Mary’s mental health. She was plagued by feelings of insecurity. Intense migraine headaches contributed to a volatile temper. There are many reports of spousal abuse inflicted upon the husband by the wife. Her unusual behavior caused some in Congress to question her sanity and her loyalty to the nation during the Civil War, prompting the President to go to the Capitol to testify to the fact that she was not a traitor.

After seeing her husband murdered in an act of unquestioned insanity, Mary’s mental state deteriorated rapidly. She grew paranoid and became convinced that someone was trying to poison her. Her spending habits, which had never been very disciplined, took an alarming turn. While complaining that she was nearly destitute, she simultaneously went on wild spending sprees. She was known to walk around with as much as $56,000 in government bonds sewn into her petticoats for safekeeping. She also fell under the spell of spiritualists as she sought to reconnect with her deceased husband.

In 1875, her son, Robert Todd Lincoln, was forced to initiate court proceedings to have her committed to an asylum. She attempted to avoid this indignity by committing suicide. Fortunately, an alert pharmacist recognized what she was trying to do and gave her a placebo instead of the laudanum she intended to use to end her life.

Henry Rathbone and Clara Harris

Maj. Henry Rathbone was in shock when President Lincoln was felled by the assassin’s bullet, but he quickly recovered and sprang into action. He made a grab for Booth, but the assassin responded by slashing the officer’s arm with a dagger. Although badly injured, he made another grab for Booth as he attempted to leap from the presidential box. This threw the assailant off balance, causing him to land awkwardly on the stage and break his leg.

Rathbone helped move the fatally-wounded president across the street to the Peterson House. Shortly thereafter, Rathbone passed out from blood loss. The injury inflicted by Booth had severed an artery.

Rathbone recovered and married Clara two years later. For a while, it appeared that they had found happiness, despite the horror they witnessed together at Ford’s Theater.

It wasn’t long, though, before Rathbone’s mental state began to deteriorate. He grew paranoid and was increasingly convinced that Clara was cheating on him. He also felt that she paid more attention to their children than to him.

The Rathbones moved to Germany, where he sought a diplomatic assignment. The state of his mental condition was so evident, however, that it was affecting his career, and his hopes were not realized.

Inexplicably, on December 23, 1883, Rathbone erupted in a fit of rage and attacked his children. When Clara attempted to intervene, he turned his rage on her. He shot and stabbed her. Seeing her lifeless body, he was overcome by the horror of what he had done and stabbed himself in the chest five times in an attempt to take his own life.

Rathbone was unsuccessful in his suicide attempt. He was charged with murder, but it was evident that he was clinically insane. He was committed to an insane asylum in Hildesheim, Germany, where he spent the rest of his life.

John Wilkes Booth

There can be no question that John Wilkes Booth was out of his mind. His rage and bitterness at the Confederacy’s loss of the Civil War caused him to commit one of the most infamous crimes in history.

It was madness to conceive of the plot. It was madness to think he could pull it off without consequences to himself. It was madness to think he would be honored instead of vilified for his crime.

Had it not been for the timely intervention by Maj. Rathbone, perhaps he would have escaped. We will never know because the injuries he sustained after leaping from the presidential box upended his escape plans. Twelve days after pulling the trigger, Booth was himself killed by a bullet.

Thomas H. “Boston” Corbett

The man who killed John Wilkes Booth was Thomas H. “Boston” Corbett. He worked as a hatter before the war and had already developed a bit of a reputation for eccentric behavior. Actually, “eccentric” doesn’t begin to describe it. On July 16, 1858, he abruptly snatched up some scissors, dropped his trousers, and castrated himself. Then, as if nothing extraordinary had taken place, he calmly got dressed and went out for a prayer meeting.

This disturbing behavior did not disqualify him from military service. When the Civil War began, he left that profession and enlisted as a private in Company I of the 12th Regiment New York Militia in April 1861. Almost from the beginning, his “eccentric behavior” was an issue. He was disciplined for his open criticism of officers and for holding unauthorized meetings. Despite being sent to the guardhouse for several days for reprimanding a senior officer, he refused to change his behavior. It led to his court-martial and a sentence of death by firing squad in August 1863. Before the sentence could be carried out, however, it was commuted, and Corbett was discharged from service.

The next year he re-enlisted, this time with Company L, 16th New York Calvary Regiment. One year after that, Corbett’s regiment was given a mission: find and apprehend John Wilkes Booth. On April 26, 1865, it appeared as if that mission was about to be fulfilled. Booth had been located, taking refuge in a tobacco barn.

The order was given that Booth should be taken alive. Soldiers surrounded the barn to prevent the fugitive’s escape. Then, in an effort to get him to abandon his hiding spot, they set fire to the barn.

Corbett was positioned near a large crack in the barn wall and was able to see Booth. Although he knew the order that Booth was not to be harmed came all the way from Secretary of War Edwin Stanton, Corbett believed exigent circumstances justified disobeying the order. He said that he saw Booth aiming his rifle at him, so he took a shot at the assassin. The bullet found its mark, passing through Booth’s head, entering at almost the same spot where Booth’s bullet struck President Lincoln. Two hours later, Booth was dead.

When asked why he had disobeyed orders, Corbett answered, “Providence directed me.”

Corbett was arrested and sent to Washington, D.C. to be court-martialed. Secretary Staton personally questioned Corbett about the circumstances of the shooting and heard Corbett claim self-defense. He insisted he had not shot to kill but only to wound. After contemplating this, Stanton said, “The rebel is dead. The patriot lives; he has spared the country expenses, continued excitement and trouble. Discharge the patriot.”

Corbett instantly transformed from prisoner to national hero. Cheering crowds greeted him as he walked out of the War Department. As well-wishers sought his autographs, he told the crowd, “I aimed at his body. I did not want to kill him….I think he stooped to pick up something just as I fired. That may probably account for his receiving the ball in the head. [W]hen the assassin lay at my feet, a wounded man, and I saw the bullet had taken effect about an inch back of the ear, and I remembered that Mr. Lincoln was wounded about the same part of the head, I said: “What a God we have…God avenged Abraham Lincoln.”

It wasn’t long before Corbett’s account of the events of that fateful night fell under suspicion. Eyewitnesses who were near Corbett said he never fired his gun. They claimed he came forward and took credit for the shooting only when no one else did. Additionally, the owner of the farm and his son both stated that they saw Booth at the time he was shot and that he was not pointing his gun at anyone.

Despite this, Corbett enjoyed national fame and received $1,653.84 (equivalent to $28,000 in 2020) as his portion of the bounty for bringing in Booth. This was more than eight times his annual salary of $204 as a sergeant in the army.

After leaving military service in August 1865, Corbett returned to his pre-war work as a hatter. He was also an itinerant Methodist lay preacher, traveling around the New England area.

The erratic behavior that got him in trouble at the beginning of the war followed him in his post-war life. He was fired from several jobs because of erratic and fanatical behavior. He tried to make up for the lost income by going on the public speaking circuit, hoping to draw crowds with stories about killing Booth and becoming “Lincoln’s Avenger.” His lectures were rambling and frequently incoherent. This, and his increasingly-erratic behavior, caused him to fall out of favor in this vocation.

Acquaintances started to grow alarmed about Corbett’s increasing paranoia. He was convinced that highly-placed government operatives were conspiring against him because he had deprived them of the glory of prosecuting Booth. He took to carrying a pistol for self-defense, but as his paranoia deepened, he was known to pull it out and brandish it at strangers and even close friends in moments of intense distrust.

In 1878, he relocated to Concordia, Kansas, and tried to make a fresh start. He acquired some property through homesteading and built a dugout home. He continued to work as an itinerant preacher, holding revival meetings whenever he could.

In January 1887, Corbett was elected Assistant Doorkeeper in the Kansas House of Representatives. His erratic and paranoid behavior did not endear himself to the public or the elected representatives, however. On more than one occasion, cooler heads had to step in and prevent him from brandishing his pistol at visitors and legislators at the statehouse.

On February 15, just six weeks into his job, he was arrested for chasing officers of the House of Representatives with his pistol. A judge committed him to the Topeka Asylum for the Insane, where he remained until his escape on May 26, 1888. He rode as far as Neodesha, Kansas, where he said he was going to Mexico. Whether he did or went to Hinckley, Minnesota, remains a matter of historical debate. There is, however, a “Thomas Corbett” appearing on the list of dead and missing from the Great Hinkley Fire of 1894.

It would be easy to make a connection between the insanity that took place in the president’s box at Ford’s Theater on that fateful night and the insanity that plagued Lincoln’s Avenger. Modern medicine points to another possible explanation for why Boston Corbett became as mad as a hatter: it is because he actually was a hatter.

The process for making hats in those days relied heavily on mercury. Today, we recognize the harmful effects of physical contact with the substance, but in the 19th century, it was a different story. Hatmakers used mercury for making felt hats and breathed the toxic vapors day in and day out. The mercury causes damage to the nervous system, producing symptoms such as drooling, twitching, paranoia, hallucinations, and agitation. The expression “mad as a hatter” originated from this unfortunate side-effect of the profession.

If the insanity that passed between those involved in the drama we know as the Lincoln assassination was contagious, then where did it start? Could it have begun with the man who brought it to an end?