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The Barrel Maker's Army: When a Private Company Went to War Against American Workers
Illuminating History's Strangest Corners | Issue #13 | December 2025
In 1892, America's largest standing army didn't answer to the President or Congress. It answered to paying customers.
The Pinkerton National Detective Agency employed 2,000 active agents and could mobilize 30,000 reserves—more men than the entire United States military, which had fewer than 30,000 soldiers on active duty. 1
Read that again. A private company, accountable only to whoever could afford their services, commanded a force larger than the federal government's. They could cross state lines pursuing anyone they deemed a criminal. They maintained the world's largest database of photographs and criminal records. They'd protected presidents and tracked down notorious outlaws.
But by the 1890s, they'd discovered something far more profitable than catching train robbers: corporations would pay enormous sums to have the Pinkertons crush their striking workers.
This is the story of how a Scottish barrel maker accidentally created America's first private military company—and how it took a massacre in Pennsylvania for Congress to finally ask whether that was a good idea.
The Barrel Maker Who Stumbled Into History
Allan Pinkerton had no intention of becoming America's first detective. He just wanted to make barrels.
Born in Glasgow, Scotland in 1819, Pinkerton was a cooper—a skilled craftsman who made barrels and kegs for breweries.2 He was also a political radical involved in the Chartist movement, which demanded democratic reforms and scared the hell out of British authorities. When police came looking for him in 1842, he fled to America with his new bride and settled near Chicago.
Allan_Pinkerton-Brady's National photographic Galleries, Public domain, via Wikimedia Commons
He opened a cooperage in the small town of Dundee. He made good barrels. He charged fair prices. The business thrived.
Then, in 1847, something happened that would change American law enforcement forever.
While gathering wood on a nearby island in the Fox River, Pinkerton stumbled upon a gang of counterfeiters. 3 He didn't confront them—he watched. He noted their patterns, their comings and goings, their habits. Then he informed the sheriff. When the gang was arrested, Pinkerton became a local celebrity.
People noticed. Banks noticed. Railroads noticed.
In 1850, Chicago made him the city's first police detective. A year later, he founded the Pinkerton National Detective Agency. 4 Their logo was an unblinking eye above the motto "We Never Sleep"—a slogan so iconic it gave birth to the term "private eye."
Pinkerton's_National_Detective_Agency_-__We_Never_Sleep.__Nova Scotia Archives, No restrictions, via Wikimedia Commons
What made the Pinkertons revolutionary wasn't just their investigative skill. It was their reach. They were a private police force that could move across local, county, and state boundaries in pursuit of criminals—something public police forces of the era couldn't do. 5 In a fragmented, pre-FBI America, the Pinkertons were the only organization that could track a criminal from New York to California.
Railroads hired them to catch train robbers. Banks hired them to investigate thefts. They solved high-profile cases, including the $700,000 Adams Express Company robbery in 1866—the largest heist in American history at the time.
In February 1861, while investigating a railroad case in Baltimore, Pinkerton operatives uncovered an apparent assassination plot against President-elect Abraham Lincoln.6 Pinkerton warned Lincoln, whose travel route was secretly changed. Whether the plot was real remains debated, but the publicity made Pinkerton a national name.
During the Civil War, Lincoln hired Pinkerton agents as spies and bodyguards. Pinkerton himself conducted espionage operations, traveling under the pseudonym "Major E.J. Allen." These activities preceded and laid the groundwork for the United States Secret Service. 7
Pinkerton_Lincoln_McClernand_Alexander Gardner, Public domain, via Wikimedia Commons
After the war, the agency exploded. They chased Jesse James. They hired Kate Warne in 1856—America's first female detective. By the early 1870s, they had the world's largest collection of criminal photographs and maintained a vast database of criminal activity. 8 They opened branch offices in every state.
But then they discovered something even more lucrative than catching criminals.
The New Threat: Labor Unions
When American Unions Came To Be
The labor movement was young, fragile, and terrifying to industrialists:
• 1869 – Knights of Labor founded (America's first major national labor organization)
• 1876 – Amalgamated Association of Iron and Steel Workers established (the union that would represent Homestead workers)
• 1886 – American Federation of Labor founded
By 1892, unions had existed as a real force for barely two decades. American corporations were still figuring out how to deal with this new threat to their absolute control. Many found the same answer: hire the Pinkertons.
Knights_of_Labor_Declaration_Document. Image edited Ulrich Lange, Dunedin, New Zealand, Public domain, via Wikimedia Commons
The Molly Maguires: When Unions Failed, Violence Filled the Vacuum
Named after a legendary Irish widow who resisted evictions in 1840s Ireland, the Molly Maguires emerged not as pure terrorists or heroes, but as the result of failed labor organizing.
In 1864, Pennsylvania coal miners formed the Workingmen's Benevolent Association (WBA), the region’s first real union. It forbade violence but also favored its own leadership and discriminated against Irish workers. In response, Irish miners organized the Ancient Order of Hibernians (AOH), a fraternal society that offered mutual aid and, allegedly, cover for more militant action.
Coal companies controlled everything—housing, stores, even police. Miners worked in lethal conditions. In 1869, a mine collapse killed 179 workers, mostly Irish, because the owner refused to fund a second escape shaft. Miners were paid in company scrip redeemable only at company stores, leaving many in perpetual debt—what one owner called “semi-slavery.”
The official story claims that between 1862 and 1876, the Molly Maguires murdered sixteen mine supervisors, bosses, and officials.
The reality is less clear. After the WBA collapsed following a failed 1875 strike, violence surged—six of the sixteen killings occurred that summer alone. Were the Mollys a coordinated conspiracy? Or were desperate Irish miners turning to violence after legal organizing had failed and courts, dominated by Welsh, German, and English judges, shut them out?
Coal company president Franklin B. Gowen seized the moment. In 1873, he hired Pinkerton agent James McParland to infiltrate the AOH. For two years, McParland gathered names, attended meetings, and befriended suspects. His testimony sent twenty Irish immigrants to the gallows between 1877 and 1879—ten on a single day, June 21, 1877, remembered as “Black Thursday.”
There was no forensic evidence, no corroborating witnesses, and no Irish Catholics on the juries—only McParland’s reports to the coal company that employed him. Prosecutors worked for railroads and mining companies. Gowen himself served as star prosecutor.
A century later, Pennsylvania issued posthumous pardons to several men, acknowledging they likely never received fair trials. Historians remain divided: were the Mollys a violent underground network, or a manufactured crisis used to crush Irish organizing?
What is certain: the Molly Maguires are recognized as “the first worker-only labor movement in American history”—and their destruction cemented the Pinkertons’ new playbook. Infiltrate. Collect intelligence. Provide damning testimony. Break the union.
The coal companies won. The Irish lost. And the Pinkertons proved their value.
Pinkerton_escorts_hocking_valley_leslies_From a sketch by Joseph Becker ; Hyde, Public domain, via Wikimedia Commons
In the 1870s, Franklin B. Gowen, president of the Philadelphia and Reading Railroad, hired the Pinkerton Agency to investigate labor unions in his company's mines. 9 This marked a turning point. 10 His testimony led to twenty executions. Whether the Molly Maguires were actually a violent conspiracy or simply a labor organization demonized by corporate interests remains disputed. What's certain is that the Pinkertons had found a lucrative new business model: selling surveillance and force to companies fighting their own workers.
The agency didn't hide this. They advertised openly. Their services included infiltrating unions to gather intelligence, providing armed guards to protect strikebreakers, and supplying "preventive patrols"—private armies corporations could rent. 11
Between 1866 and 1892, the Pinkerton Agency provided services in 70 different labor disputes. 12 They became mercenaries, deploying armed force wherever capital needed it. The model was simple: send in Pinkerton agents to occupy a factory or mill, protect the strikebreakers brought in to replace union workers, and hold the facility until the strike collapsed from economic pressure.
By 1892, the pattern was established: if your workers strike, hire the Pinkertons. They'll break it.
Henry Clay Frick, manager of Andrew Carnegie's steel empire, was a repeat customer. When workers at the Homestead Steel Works refused to accept a 22% wage cut in summer 1892, Frick didn't hesitate.
Promise_and_Performance_Political_Cartoon_Andrew_Carnegie_sitting_on_bags_of_money_Homestead_Strike_1892_Unkonwn Author_St. Paul daily globe. (Saint Paul, Minn.), 03 July 1892
His plan was straightforward: hire 300 Pinkerton agents, sneak them into the mill before dawn, have them occupy the facility, then bring in strikebreakers to restart production under armed protection. The Pinkertons would hold the mill like a military garrison until the strike collapsed.
There was just one problem: the workers controlled the town. Every road leading to the mill was blocked. The only way to get 300 armed men past thousands of striking workers was by water.
So Frick put them on barges and sent them up the Monongahela River in the middle of the night.
July 6, 1892: When the Invasion Failed
The workers were waiting.
Three hundred Pinkerton agents assembled at Davis Island Dam on the Ohio River at 10:30 p.m. on July 5. They were given Winchester rifles, loaded onto two covered barges, and towed upriver toward Homestead. 13 Many had been recruited just days earlier from flophouses in Boston and New York at $2.50 per day, unaware of what their assignment actually was. 14 They weren't told they were heading into a strike zone. They weren't told that ten thousand steelworkers and their families would be waiting.
The plan was to land at the mill's private dock before sunrise, occupy the buildings, and hold them until Frick could bring in strikebreakers. The barges weren't meant to be prisons—they were meant to be transport, a way to sneak an occupying force past the workers who controlled all the roads into Homestead.
The barges arrived just past 4:00 a.m. on July 6. But the workers had torn down the barbed-wire fence around the mill and occupied the grounds themselves. As the Pinkertons tried to disembark and take control of the mill, someone fired a shot. Within seconds, both sides opened fire.
In the initial exchange, seven workers and three Pinkerton agents were killed. 15 The plan to occupy the mill failed in the first minutes. The Pinkertons retreated into their barges with no way to advance and no way to escape. What followed was a thirteen-hour siege.
Workers brought a Civil War cannon and aimed it at the barges. They rolled burning freight cars toward them. They pumped oil into the river and set it on fire. They threw dynamite.
Inside the barges, the temperature soared past 100 degrees. Wounded men lay bleeding, "piteously begging for someone to give them a drink of water, but no one dared to get a drop."16 Bullets punched through the wooden walls continuously. By afternoon, the Pinkertons mutinied against their own officers—the reservists, recruited under false pretenses expecting simple guard duty, refused to fight anymore. 17
Homestead_Strike_-_Barges_on_fire_Engraving by Charles Mentes, after photograph by B.H.L. (or B.L.H.) Dabbs (Pittsburgh), Public domain, via Wikimedia Commons
At 5:00 p.m., the Pinkertons raised a white flag.
The workers agreed to let them surrender in exchange for safe passage to the train station. Three hundred twenty-four Pinkerton agents filed off the barges, weaponless and terrified.18
The guarantee didn't hold.
As the Pinkertons walked through Homestead, the entire town descended on them. Men, women, children—people who'd watched neighbors shot, who'd heard gunfire all day. They beat the Pinkertons with fists, sticks, stones, rifle butts. About half sustained injuries, some serious. 19 Union leaders tried to maintain order, forming protective lines, but the crowd was too angry, too large.
Behind them, workers set the barges on fire. They burned through the night, collapsing into the river in showers of sparks.
The Pinkertons were loaded onto a train and sent back to Pittsburgh, bloodied and broken. Frick's plan to occupy the mill with a private army had failed catastrophically. The occupying force never made it past the dock.
Homestead_Strike_-_Mob_attacking_Pinkerton_men_Engraving by Charles Mentes, after photograph by Darbis (Pittsburgh), Public domain, via Wikimedia Commons
The Reckoning
The Battle of Homestead became a national scandal. A popular ballad swept the country: "Father Was Killed by the Pinkerton Men." Newspapers published horrified accounts. One reverend called the Pinkertons "a blot on civilization and a disgrace to this country."
Congress launched immediate investigations. Both the House and Senate held hearings specifically into the Pinkerton Agency's role. Testimony revealed the agency's involvement in over 70 labor disputes between 1866 and 1892. Witnesses described infiltration, intimidation, and violence carried out by a private company accountable to no one but paying clients.
The evidence was overwhelming: a private corporation had assembled a force larger than the United States military and deployed it against American citizens exercising their right to strike.
On March 3, 1893, Congress passed the Anti-Pinkerton Act. 20 The law was simple: "An individual employed by the Pinkerton Detective Agency, or similar organization, may not be employed by the Government of the United States or the government of the District of Columbia."
The federal government could no longer hire the Pinkertons. States began passing similar laws. Ohio outlawed them entirely.
Congress had decided: in a democracy, there was no place for a private army larger than the nation's military.
But for the workers, the victory was hollow.
The Workers Lost Anyway
Four days after the battle, Pennsylvania deployed 8,500 National Guard troops to Homestead. Carnegie Steel reopened with strikebreakers under military protection. The strike continued for months, but without access to the mill, the union's power was broken.
Despite the dramatic failure of the Pinkerton invasion, Frick achieved his goal. By November 1892, the Amalgamated Association collapsed. Union membership plummeted from 24,000 to 10,000. 21 The daily wages of highly skilled workers at Homestead shrank by one-fifth over the next fifteen years, while their shifts increased from eight hours to twelve.
Andrew Carnegie—conveniently vacationing in Scotland during the battle—returned to union-free plants and massive profits. He spent the rest of his life building libraries and remaking himself as a philanthropist.
The Pinkertons won where it mattered: in breaking the union and establishing that corporate force, even when publicly humiliated, ultimately prevails.
What Happened to the Pinkertons
The Anti-Pinkerton Act didn't put them out of business—it just meant the government couldn't hire them. Corporations still could.
By the 1930s, after the La Follette Committee hearings exposed continued labor spying, the agency finally shifted away from union work. 22 They focused on corporate security and investigating fraud. In 1965, they renamed themselves Pinkerton's Incorporated. In 1999, the Swedish security giant Securitas AB purchased the company for $384 million. 23
Today, Pinkerton still exists—not as an independent company, but as a division of Securitas, one of the world's largest security firms with over 350,000 employees globally. 24 They provide risk management, corporate investigations, and security consulting. The name remains because it still carries weight.
The Template Goes Global
The Anti-Pinkerton Act remains law, codified in 5 U.S.C. § 3108. 25 Courts have interpreted it to prohibit the government from hiring "quasi-military armed forces for hire."
But the Pinkerton model didn't disappear. It evolved.
In the 1990s and 2000s, Private Military Companies exploded. Blackwater (now Academi), DynCorp, Triple Canopy—modern Pinkertons operating in war zones instead of mill towns. The Russian mercenary group Wagner operates globally with the same model: private force for hire, accountable primarily to whoever pays. G4S, with over 500,000 employees, is essentially a global Pinkerton agency.
In 2020, Amazon hired Pinkerton—the same company, now owned by Securitas—to monitor warehouse workers for union activity. Internal documents revealed that Pinkerton operatives were "inserted" into an Amazon warehouse in Poland to gather intelligence on workers. 26 In 2022, Starbucks hired former Pinkerton employees as part of union-busting efforts.27
The language is more polite now. "Security consultants" instead of "strikebreakers." "Workplace safety monitors" instead of "union infiltrators." But the transaction remains: corporations with enough money can purchase surveillance and intimidation.
The barrel maker who stumbled upon counterfeiters in 1847 created a template for how corporations could wield private force outside democratic control. Congress passed a law in 1893 saying the government couldn't hire them—but never asked whether anyone should be able to.
The Pinkertons adapted. The model went global. In 1892, it took a massacre for Congress to act. Today, the same system operates worldwide, just sophisticated enough to avoid headlines, just legal enough to continue.
The question isn't whether we've learned anything from Homestead. It's whether we ever intended to.
What's Next in Obscurarium?
What bizarre historical phenomenon should we investigate next? Drop us a line at [email protected].
1 By the early 1890s, the Pinkerton National Detective Agency had 2,000 active agents and 30,000 reserves. The U.S. standing army had fewer than 30,000 soldiers. HISTORY, "10 Things You May Not Know About the Pinkertons."
2 Allan Pinkerton was born in Glasgow, Scotland, on August 25, 1819. Library of Congress, "Today in History - August 25."
3 While gathering wood, Pinkerton discovered a gang of counterfeiters on an island in the Fox River. PBS, "Allan Pinkerton's Detective Agency."
4 In 1850, Pinkerton became Chicago's first police detective and founded the North-Western Police Agency with Edward Rucker. A year later, he founded the Pinkerton National Detective Agency. Pinkerton (detective agency), Wikipedia.
5 Frank Moran described the agency as "a private police force that could move across local, county, and even state boundaries." Encyclopedia.com, "Pinkerton National Detective Agency."
6 In February 1861, Pinkerton operatives uncovered an apparent assassination plot against President-elect Lincoln in Baltimore. Library of Congress, "Today in History - August 25."
7 Pinkerton's Civil War intelligence activities preceded and laid groundwork for the U.S. Secret Service. Pinkerton (detective agency), Wikipedia.
8 By the early 1870s, the agency had the world's largest collection of mugshots and criminal database. Legends of America, "Pinkerton Detective Agency."
9 In the 1870s, Franklin B. Gowen hired the agency to investigate labor unions in company mines. Pinkerton (detective agency), Wikipedia.
10 James McParland, using alias "James McKenna," infiltrated the Molly Maguires. His testimony led to twenty executions. Ibid.
11 Pinkerton Agency advertisements from the 1880s. History Matters, "Spies for Hire: Advertising by the Pinkerton Agency."
12 Between 1866 and 1892, Pinkertons participated in 70 labor disputes. PBS American Experience, "The Strike at Homestead Mill."
13 Three hundred Pinkerton agents assembled at Davis Island Dam at 10:30 p.m. on July 5, 1892, given rifles, and placed on barges. Homestead Strike, Wikipedia.
14 Many agents were hired from lodging houses at $2.50/day and were unaware of their assignment. Ibid.
15 Seven workers and three Pinkerton agents died in the initial exchange. AFL-CIO, "1892 Homestead Strike."
16 Pinkerton agent testimony about conditions inside the barges. PBS, "The Strike at Homestead Mill."
17 Pinkertons mutinied against their officers. Libcom.org, "The Homestead Strike, 1892."
18 Total of 324 Pinkerton agents and crew surrendered. Homestead Strike, Wikipedia.
19 About half of the Pinkertons sustained injuries during the gauntlet. Battle of Homestead Foundation.
20 Anti-Pinkerton Act, March 3, 1893, codified at 5 U.S.C. § 3108.
21 Amalgamated Association collapsed by November; membership dropped from 24,000 to 10,000 by 1894. AFL-CIO, "1892 Homestead Strike."
22 Pinkertons diversified from labor spying following La Follette Committee hearings in 1937. Pinkerton (detective agency), Wikipedia.
23 Securitas AB purchased Pinkerton for $384 million in 1999. Company acquisition records.
24 Securitas AB employee count and Pinkerton as division. Securitas corporate website, 2024.
25 Anti-Pinkerton Act codified at 5 U.S.C. § 3108; courts interpret as prohibiting quasi-military forces for hire.
26 Amazon hired Pinkerton (division of Securitas) in 2020. Internal documents showed Pinkerton operatives were "inserted" into Amazon warehouse in Wroclaw, Poland in November 2019. Vice/Motherboard, November 2020; NPR, "Amazon Reportedly Has Pinkerton Agents Surveil Workers."
27 Starbucks hired former Pinkerton employees in 2022 as part of union-busting efforts. Pinkerton (detective agency), Wikipedia; various labor reporting.
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