AMERICA AT WAR
The Messages That Crossed Long Island Sound
How George Washington’s Culper network turned merchants, riders, and boatmen into a working intelligence system during the Revolutionary War.
The Culper Spy Ring moved reports from British-held New York through a civilian relay of riders, boatmen, codes, and concealed writing. Its intelligence helped Washington respond to a British threat against the French force at Newport.
In British-held New York, getting a military report out of the city could be as dangerous as gathering it. George Washington’s answer was not a single heroic spy, but a relay: civilians who could collect information, carry it across Long Island, move it over the Sound, and pass it to Continental officers for evaluation.
In 1778, Washington commissioned Major Benjamin Tallmadge to build a permanent intelligence network in and around occupied New York. The network later known as the Culper Spy Ring linked Manhattan, Long Island, Connecticut, and Washington’s command through aliases, coded dispatches, and carefully divided responsibilities. [1]
A network built around ordinary lives
Tallmadge, a Continental officer, managed the operation. Most of its participants were civilians whose regular work gave them reasons to travel, conduct business, and remain in place behind British lines. [4]
Abraham Woodhull, a farmer from Setauket on Long Island, used the alias Samuel Culper Sr. Robert Townsend, a Manhattan merchant and journalist, gathered intelligence under the name Samuel Culper Jr. Their assumed names were more than theatrical flourishes. They helped protect people whose real identities could put them in serious danger if correspondence were seized. [1]
Tallmadge also limited who knew what. Washington knew Woodhull’s identity, but Townsend’s identity was withheld from him. That separation reduced the number of people who could expose an operative if questioned or captured. [1]
The route out of New York
The network depended on a chain of handoffs rather than one uninterrupted journey. Austin Roe, a Setauket tavern keeper, made a roughly 110-mile round trip on horseback between Long Island and Manhattan, carrying coded material. [4]
From Setauket, Caleb Brewster carried dispatches across Long Island Sound in whaleboats to Connecticut. The crossing connected the New York side of the network to Continental-controlled territory, where the information could move onward to Tallmadge and Washington. [5]
The route has attracted its share of legend. Long Island tradition says Anna Smith Strong used a black petticoat and handkerchiefs on a clothesline to signal Brewster about a landing place. The story may reflect a real role in the network, but surviving wartime records do not conclusively establish that signaling system. [5]
What the evidence does show is a system designed to avoid concentrating risk in one person. A report could move from a source in Manhattan to a courier, then to Long Island, across open water, and into the hands of Continental officers.
Numbers, aliases, and invisible writing
Tallmadge’s code book assigned numbers to names, places, common words, and letters. It contained 763 entries: 711 meant George Washington, while 727 meant New York. A captured message filled with numbers was less useful without the matching code book. [2][3]
The ring also used sympathetic stain, an invisible ink supplied by James Jay. With the proper reagent, hidden writing could be revealed in an otherwise ordinary letter. [1]
Neither method made the correspondence safe by itself. The strength of the system came from combining codes and concealed writing with aliases, separate couriers, and limited knowledge among its participants.
A warning from New York
The network’s reports mattered because Washington could use them in planning. In 1780, the Culpers warned him that British forces planned to attack the French expeditionary fleet at Newport, Rhode Island. Washington responded with maneuvers that suggested an American move against New York, helping persuade British commander Sir Henry Clinton to abandon the attack. [1]
That episode did not decide the war on its own. It did, however, help protect the French force that had recently arrived in North America—an alliance Washington needed to preserve.
The ring was also connected to the crisis surrounding Benedict Arnold’s plot to surrender West Point. When Major John André was captured behind American lines while using the name John Anderson, Tallmadge recognized the suspicious circumstances. André’s capture helped expose Arnold’s plan. [1]
A secret kept for generations
The British evacuated New York on November 25, 1783. By the end of the war, none of the Culper Ring’s core civilian spies had been captured or publicly unmasked by the British. [1]
Robert Townsend never publicly identified himself as Samuel Culper Jr. In 1929, researcher Morton Pennypacker connected Townsend to the Culper dispatches through handwriting comparison, revealing the identity of a central figure in the network long after the fighting had ended. [5]
The Culper Ring’s importance lies in its method. Washington and Tallmadge created a continuing intelligence operation that could move information through hostile territory without requiring every participant to know the whole plan. Its messages crossed roads, shorelines, and Long Island Sound before reaching an army that needed more than courage to survive.
Frequently asked questions
What did 711 and 727 mean in the Culper Code Book?
In Tallmadge’s 763-entry code book, 711 stood for George Washington and 727 stood for New York. The code substituted numbers for names, places, common terms, and letters. [2][3]
Who was Agent 355?
The supplied evidence does not identify a specific person as Agent 355. Popular accounts often connect the number to a woman who aided the ring and later died on the prison ship *HMS Jersey*, but that account is not conclusively supported by wartime documentation. In the Culper code book, 355 meant “lady,” rather than serving as proof of a particular agent’s identity. [2][5]
How did Robert Townsend remain anonymous for so long?
Townsend used the alias Samuel Culper Jr., and Tallmadge restricted knowledge of agents’ real identities. Townsend did not publicly disclose his role. Pennypacker identified him in 1929 by comparing his handwriting with Culper dispatches. [1][5]
TIMELINE
Key moments
Sources
- Culper Spy Ring — George Washington's Mount Vernon
- The Culper Code Book — George Washington's Mount Vernon
- Secret Codes for Washington's Spies — Library of Congress
- Three Key Intelligence Contributions of the Little-Known Culper Ring — Central Intelligence Agency
- Caleb Brewster and the Culper Spy Ring — Connecticut Humanities
RELATED STORIES