Culper Spy Ring: George Washington’s Secret Weapon Against the British

Here's how George Washington built a spy network that used codes, invisible ink and dead drops to fight the British.

The Culper Spy Ring was one of the best-kept secrets of the American Revolution. While George Washington’s army struggled to survive in the field, a small network of spies worked behind British lines, passing along intelligence through coded messages, invisible ink and dead drops.

Their work helped Washington understand what the British were planning, often before they made their next move.

As the AMC original series TURN: Washington’s Spies depicted, Abraham Woodhull was caught in July 1778 by a Continental naval patrol for smuggling and trading with the enemy. He was later recruited as a spy for the Patriots.

The series also introduced viewers to several key members of the Culper Spy Ring, including Woodhull, Major Benjamin Tallmadge, Robert Townsend and Caleb Brewster, along with the group’s use of early spy techniques such as codebooks, invisible ink and dead drops.

*Major Benjamin Tallmadge was one of the key members of the Culper Spy Ring, which gathered intelligence on the British for George Washington.*

Nearly 250 years later, the Culper Spy Ring remains the most famous spy network of the American Revolution. It was also so secretive that only its key members have been identified with certainty. During the war, the British only definitely identified Brewster as a spy.

Why Revolutionary War Spies Mattered

Throughout the history of armed conflicts, spies have played a pivotal role in shaping the outcome of wars. One of the earliest references to spycraft in a military sense appears in Sun Tzu’s The Art of War, written in the 4th century BC. The Chinese theorist wrote, “One who knows the enemy and knows himself will not be endangered in a hundred engagements.”

During the 18th century, when two or more European powers were at war nearly nine out of every 10 years, governments constantly sought ways to gather intelligence on their rivals. During the American Revolution, spycraft became especially important because Washington’s army often faced a better-supplied, better-equipped British force.

It’s doubtful General George Washington had read or even known about The Art of War, but historians have noted that his use of deception, intelligence gathering and attempts to avoid direct, decisive battles against a superior force mirrored some of the same principles. Perhaps two great minds just thought alike.

George Washington Learned Intelligence Before the Revolution

It was from his experience in the French and Indian War that General Washington first learned the importance of intelligence and espionage. During an expedition in the 1750s, a young Washington was tasked with gathering intelligence on French movements.

He used Native American scouts and interrogated deserting French soldiers to better determine the enemy’s strength and intentions. He saw the importance of on-the-ground surveillance long before he commanded the Continental Army.

In a 1777 letter to Colonel Elias Dayton, Washington wrote: “The necessity of procuring good Intelligence is apparent & need not be further urged. All that remains for me to add is, that you keep the whole matter as secret as possible.”

Following the war, a British intelligence agent was credited with writing, “Washington did not really outfight the British. He simply out-spied us.”

Early Revolutionary War Intelligence Operations

Even before the outbreak of armed conflict, both sides were heavily engaged in espionage. Thomas Gage, the royal governor of Massachusetts, dispatched two individuals to travel to Concord in March 1775, a month before the “shot heard ‘round the world” was fired, to gather information about the Patriots’ intentions and determine their strength.

When the British Redcoats marched to Concord in April, it didn’t come as a surprise. It has been speculated that some colonists had already passed along information about British plans.

Benjamin Tallmadge’s Culper Spy Ring code book helped Washington’s spies turn names, places and military details into numbers, allowing them to report British troop and ship movements from occupied New York with greater secrecy.

Both armies relied on second-hand information to track troop movements, unit strength and soldiers’ morale. The British turned to Loyalist sympathizers, while the Patriots recruited supporters of their cause.

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As the war progressed, both armies also employed misinformation by leaking false intelligence, especially about troop strength and movements.

Thanks to numerous books and the AMC TV series, the story of the Culper Ring isn’t likely to be forgotten. Its role in the American Revolution also shouldn’t be overlooked.

The Culper Spy Ring’s Biggest Wins

Operating from 1778 to 1783 in British-occupied New York, the Culper Spy Ring provided crucial intelligence on British troop movements, exposed a planned ambush by British General Henry Clinton against newly arrived French forces in Rhode Island, and warned Washington of raids aimed at dividing the Continental Army.

British Major John André offers his watch and money as a bribe after American militiamen discover papers tied to Benedict Arnold’s plot to surrender West Point to the British, a conspiracy many historians credit the Culper Spy Ring with helping expose.

The group also gathered detailed intelligence on British ship movements, fortification plans and troop strength in New York.

The Culper Ring also helped uncover the plot between American General Benedict Arnold and British Major John André, which included turning over West Point to the British.

Agent 355 and the Culper Spy Ring’s Biggest Mystery

Even today, the exact number of individuals who were part of the ring is unknown. That mystery includes “Agent 355,” a woman whose identity remains a secret even though her contribution was vital to the Patriot cause.

There is speculation that she was a woman of social prominence, perhaps from a Loyalist family. Other theories suggest she was enslaved, Townsend’s common-law wife or one of several women who passed on secrets. It’s also possible 355 was a code for a group of individuals rather than one person.

“George Washington depended on this network of selected agents that allowed him to keep a finger on the pulse of his enemy’s operations and intentions,” explained Blake McGready, program assistant at The Gotham Center for New York City History.

“The ring gathered actionable military information, transmitted it across long distances, and did so in ways that protected its members well enough to sustain reconnaissance operations from 1778 to 1783.

At the same time, intelligence gathering extended far beyond such formalized networks. Military forces also acquired useful information from intercepted correspondence, deserters, prisoners, and civilians who moved between lines.”

Washington’s Other Revolutionary War Spies

Even as the Culper Spy Ring continues to capture the imagination of history buffs, countless others played vital roles in Washington’s intelligence efforts. The majority of conspirators and agents are lost to history, much like Agent 355, even though their actions helped support American independence and eventual victory.

Among the most important of Washington’s intelligence figures was John Jay, who served as a spymaster and counterintelligence leader.

As the head of the Committee for Detecting and Defeating Conspiracies in New York, Jay directed operatives, managed intelligence networks and ran counterintelligence operations. Those efforts helped protect Washington from several plots, including a planned assassination attempt.

As the head of the Committee for Detecting and Defeating Conspiracies in New York, John Jay directed operatives, managed intelligence networks and ran counterintelligence operations for the Colonies. Today he is remembered as the first chief justice of the United States Supreme Court.

As a spymaster, Jay managed agents such as Enoch Crosby, who infiltrated Loyalist groups to provide details on British movements. Although Jay is now remembered as a diplomat and the first chief justice of the United States Supreme Court, he was also a major figure in early American counterintelligence.

Jay’s brother, Sir James Jay, also played a role by developing an invisible ink used by various spy rings.

Other spies shouldn’t be overlooked, including Hercules Mulligan, a New York tailor who acted as an independent agent and provided crucial information to Washington throughout the war.

Allan McLane, an American military officer, led a company of men that acted as a front-line intelligence unit, gathering information on British troop movements.

How the Culper Spy Ring Changed American Intelligence

Intelligence alone didn’t win the American Revolution, but it gave Washington a clearer view of British plans and helped shape the way he fought the war.

“And yet, the Revolution did change espionage operations in significant ways,” added McGready. “Throughout the war, Washington moved away from single-use scouts on reconnaissance missions, like Nathan Hale, and toward a network of agents fixed behind enemy lines.

"This secretive and stable system anticipated how later military leaders would collect and use intelligence. Ultimately, intelligence shaped the war less than the war reshaped intelligence.”

Espionage didn’t win the war, but it changed the way Washington fought it. He didn’t rely only on battlefield reports or one-time scouts. Over time, he built networks of agents who could stay behind enemy lines, gather intelligence and protect each other through secrecy, codes and distance.

That was the Culper Spy Ring’s lasting legacy. It helped Washington understand what the British were planning, but it also helped shape the future of American intelligence. The war made spies necessary. Washington made them organized.

Editor's Note: This article is part of Hook & Barrel's special series on the American Revolution highlighting the firearms and people who made a real difference in the birth of the United States. Check out the rest of the series here: