How Kate Warne, America’s First Woman Detective, Foiled a Plot to Assassinate Abraham Lincoln

In February 1861, the Pinkerton agent, posing as the disguised president-elect’s sister and caregiver, safely escorted him to Baltimore

Illustration of Kate Warne, wearing a detective's hat and holding a magnifying glass, in front of newspaper coverage of the Baltimore Plot
Kate Warne was the Pinkerton National Detective Agency's first woman operative. She died in 1868 at age 34 or 35. Illustration by Meilan Solly / Photos via Chicago History Museum, and Pixabay

On a hot summer day in 1856, detective Allan Pinkerton looked up from his desk and greeted the young woman standing in front of him. He assumed she’d misunderstood a job posting by his firm, the Chicago-based Pinkerton National Detective Agency.

As Pinkerton told the visitor, he wasn’t looking for a secretary. But Kate Warne, a 23-year-old widow and recent transplant from New York, had a different role in mind: She wanted to be his newest detective.

No American detective agency had hired a woman investigator before. But Warne made a convincing case. She could infiltrate places easily, as no one would expect a woman to be an undercover detective, and befriend the wives and girlfriends of suspected criminals. “Women have an eye for detail and are excellent observers,” she reportedly said to Pinkerton.

“What I love in that moment is she basically comes right at him and says, ‘I can see things and hear things that you’re not going to see and hear,’” explains Brad Meltzer, co-author of the 2020 bestseller The Lincoln Conspiracy: The Secret Plot to Kill America’s 16th President—and Why It Failed.

Depiction of Abraham Lincoln, detective Allan Pinkerton and bodyguard Ward Hill Lamon arriving in Washington, D.C. on February 23, 1861.
Depiction of Abraham Lincoln, detective Allan Pinkerton and bodyguard Ward Hill Lamon arriving in Washington, D.C. on February 23, 1861. Kate Warne, who'd posed as the disguised president-elect's sister, left the group after successfully delivering Lincoln to Baltimore. Photo by Kean Collection / Getty Images

Warne’s argument worked, and later that night, Pinkerton decided to take a chance on his unconventional applicant. It was a wise decision. In addition to making history as the first woman detective in the United States, Warne likely saved Abraham Lincoln’s life by helping to uncover—and thwart—a plot to assassinate him ahead of his March 1861 inauguration. “[She’s] great at ... infiltrating that world of women who are hearing and seeing [while] people are looking right past her,” says Meltzer.

“Allan was flummoxed at first,” says Brian McNary, current vice president of Pinkerton, which opened in 1850 and is now headquartered in Ann Arbor, Michigan. “It [was] really not a customarily appropriate position for a lady.”

Still, McNary adds, “She pointed out to him the advantages that her gender carried with it and the ability to gain confidences and positions of access that would be unavailable to him.”

Meltzer, for his part, says, “To this moment, we don’t know if Allan Pinkerton is just an amazing advocate for women’s rights, or he’s just a shrewd businessman who realizes she’s going to make him some money. Whatever his reason is, he hires her.”

Little is known about Warne’s early life except that she was born into a large, impoverished family in the town of Erin, New York, in 1833. Her father was a minister, and as a young woman, she took on the role of running the household, according to McNary. She longed to escape her upbringing and become an actress, but both of her parents discouraged this dream.

Photograph of Kate Warne
1866 photograph of Kate Warne Public domain via Chicago History Museum

How Warne landed on detective work as an alternative to acting is unclear. But she quickly established herself as a leading Pinkerton investigator. In 1859, for instance, she helped track down Nathan Maroney, who was suspected of embezzling from the Adams Express Company in Montgomery, Alabama. Warne replaced her Northern accent with a Southern one; befriended Maroney’s wife; and, alongside Pinkerton colleague John White, elicited a full confession from the embezzler.

Pinkerton, who’d immigrated to America from Scotland in 1842, was a cooper (maker of wooden casks and barrels) and abolitionist known for his populist views. He initially set up shop as a cooper in Dundee, Illinois, but soon became interested in police work. After serving as deputy sheriff in two Chicago-area counties, he became a special agent for the U.S. Post Office in Chicago.

In 1850, Pinkerton started his own private detective agency—the first of its kind in the country. The group handled a wide range of cases, from white collar crime to thefts to cons. According to McNary, antebellum sources suggest the expanding agency achieved a small amount of national recognition prior to the Civil War.

John Derrig, an author and retired police detective who worked as an investigator in Florida, says that Warne’s chameleonlike ability to adapt gave her a huge advantage as a detective.

“She was able to blend in well” and was very articulate, says Derrig, who published a novel about Warne in 2014. “She was able to fit in with ... the elite. She was able to go to these parties and learn different things [without them] knowing that she was working for the Pinkerton agency.”

Warne, the author continues, “dress[ed] the part or fit right into whatever situation she was in. … She was very brave, and she was comfortable doing what she was doing because she was good at it.”

Hattie Lawton and Timothy Webster
Detective Hattie Lawton with fellow Pinkerton agent Timothy Webster prior to his execution by the Confederates for wartime espionage in 1862 Public domain via Wikimedia Commons

Highly impressed with Warne’s work in Alabama, Pinkerton placed her in charge of his newly created Female Detective Bureau in 1860. She served in that role for the rest of her life, overseeing the recruitment of all of the agency’s woman detectives, including Hattie Lawton and Elizabeth H. Baker, both of whom spied for the Union during the Civil War. Exactly how many women Warne hired is unknown, but under her leadership, the Chicago-based bureau expanded into several regional Pinkerton branches. Warne personally oversaw the establishment of a Female Detective Bureau in New Orleans, notes McNary.

“Allan placed unreserved faith in her ability,” the Pinkerton vice president says. “He was fond of saying she had never failed him.”

In Pinkerton’s own words, Warne was “[o]f rather a commanding person, and with an ease of manner that was quite captivating at times, she was calculated to make a favorable impression.”

In February 1861, Warne and several Pinkerton colleagues—acting at the request of Samuel M. Felton, president of the Philadelphia, Wilmington and Baltimore Railroad—infiltrated a secessionist plot to assassinate Lincoln before he could be inaugurated as president. Felton, who had received a tip about a “deep-laid conspiracy to capture Washington, destroy all the avenues leading to it from the North, East and West, and thus prevent the inauguration of Mr. Lincoln in the Capitol of the country,” suspected that the secessionists would strike in Baltimore, the only slaveholding city (aside from the capital itself) on the president-elect’s journey from Springfield, Illinois.

Warne went undercover to unravel the plot, reprising her Maroney-era performance as a Southern belle from Alabama. Using the aliases Mrs. Cherry and Mrs. Barley, she attended parties with a cockade (the emblem of secession) emblazoned on her chest. She became friendly with the wives and sisters of the men intent on killing Lincoln, and in doing so, helped crack the case.

A Thomas Nash cartoon of the disappointed crowd that had hoped to see Lincoln during his stop in Baltimore
A Thomas Nash cartoon of the disappointed crowd that had hoped to see Lincoln during his stop in Baltimore Public domain via Wikimedia Commons

Cypriano Ferrandini, a barber from Corsica who worked in the basement of Barnum’s City Hotel, allegedly served as the secessionists’ ringleader. “Lincoln shall never, never be president,” he once said. “My life is of no consequence. I am willing to give it for his. I will sell my life for that of that abolitionist.” But Ferrandini was never indicted for his role in the conspiracy, and the details of the plot—including how many people were involved and exactly how much of a threat it posed to Lincoln—remain the subject of debate.

According to Pinkerton’s records, the most plausible plan uncovered by the agency called for the conspirators to attack Lincoln between his arrival at Baltimore’s Calvert Street Station on the afternoon of February 23, 1861, and his departure from Camden Street—about a mile away—later that day. To avoid the would-be assassins, Pinkerton snuck Lincoln into Baltimore aboard an overnight train that arrived in the city at 3:30 a.m. The president-elect pretended to be Warne’s “invalid brother,” with the woman detective posing as his caregiver. Warne gained the train conductor’s sympathy and secured an entire sleeping car for her party of four (herself, Lincoln, Pinkerton and Lincoln’s bodyguard Ward Hill Lamon). Nobody but the Pinkerton crew realized that the incoming president was on board, and Lincoln arrived in D.C. safely at 6 a.m.

Without Warne’s protection, Lincoln might not have escaped the Maryland city alive, says Meltzer. “But for Kate Warne, history potentially winds up very different,” he continues. “She’s considered such a vital part of the story. [O]n those days when they were hiding him, they saved his life.”

The president’s disguise (Lincoln wore a loose overcoat with a felt hat pulled over his face, and perhaps a shawl on his shoulders) was clever, says Meltzer, and Warne’s supposed role as a humble caregiver and sister was very believable.

“At the end of the day, what she was amazing at is understanding how people don’t look at you, depending on what they think of you,” he adds. “She keenly understood that the way men used to underestimate women was an advantage for her.”

Allan Pinkerton (left) with Abraham Lincoln and General George B. McLellan
Allan Pinkerton (left) with Abraham Lincoln and General George B. McLellan Public domain via Wikimedia Commons

Pinkerton’s logo—a big, unblinking eye with the motto “We Never Sleep”—likely originated with Warne’s role of watching Lincoln in the sleeping car, according to McNary. While Lincoln reportedly complimented Warne, saying, “I believe it has not hitherto been one of the prerequisites of the presidency to acquire in full bloom so charming and accomplished a female relation,” the detective was less effusive in her assessment of him: “Mr. Lincoln is very homely, and so very tall that he could not lay straight in his berth,” she wrote.

After the Civil War started in April 1861, Union Army commander George B. McClellan appointed Pinkerton his chief of intelligence. Warne, meanwhile, continued posing as a Southern belle, passing on information about the Confederates to her boss. Though the Pinkerton agency received much publicity for its role in preventing Lincoln’s pre-inauguration assassination and wartime counterintelligence efforts, these reports made little mention of Warne’s role, McNary says. The detective was, however, lauded in print for her other contributions to the agency, including the arrests of murderers and bank robbers.

Warne lived a remarkable but short life. She died of pneumonia on January 28, 1868, at age 34 or 35. Pinkerton, who was reportedly at her bedside when she died, arranged for Warne’s burial in the Pinkerton family plot at Graceland Cemetery in Chicago.

“There are so many operatives who gave their all and thought nothing for their own safety or advancement in the protection of rule and law, and that is good and right,” McNary says. “Among the brightest and shining stars of the history of Pinkertons, Kate Warne is probably the least known and most loved of all of them.” Among company employees, he adds, her name seems to “invoke a kind of hushed reverence. ... Her resolve and devotion just exemplified what it was to be a Pinkerton agent.”

Allan Pinkerton on horseback in 1862
Allan Pinkerton on horseback at the Antietam battlefield in 1862 Public domain via Wikimedia Commons

Pictures of Warne, Pinkerton and other Civil War–era detectives decorate the walls of Pinkerton offices around the world, “just to reinforce that sense of continuity of values with our founder,” McNary says.

“Her career was pretty shrouded because of intent. In her position, she couldn’t be a celebrity,” he explains. “There’s a lot that we don’t know about her, but I think that’s exactly how she would have liked it. She was the epitome of professionalism in our industry and our discipline.”

Warne’s death, like her life, received little fanfare. Still, an obituary published in the Democratic Enquirer recognized her as “a most remarkable woman [who] deserves a passing notice.” The Ohio newspaper continued, “She was undoubtedly the best female detective in America, if not in the world.”

Today, books like Meltzer’s and a planned biopic starring Emily Blunt as the trailblazing detective are introducing her legacy to a new generation of admirers. “Over a century later … her groundbreaking role as America’s first female detective gets the recognition it deserves,” Meltzer says. “She’s a hero, and I think the world needs to know her story.”

Get the latest History stories in your inbox?

Click to visit our Privacy Statement.