During the American Revolution, the city of New York was firmly in British hands. But here, in the very heart of the enemy, George Washington had his very own spy ring–which uncovered America’s greatest traitor.
In August 1776, shortly after the American colonial forces under George Washington lost the Battle of Brooklyn, British troops occupied Long Island and established it as a major base for the Royal Navy and the headquarters for General Henry Clinton, the British Commander-in-Chief. The American revolutionaries saw this concentration of British forces as an opportunity to learn what the English were up to, and sent a number of spies in to obtain intelligence information about troop movements and naval operations. One of these, Nathan Hale, was caught by the British and unceremoniously hanged without trial in September.
In 1778, General Washington appointed a young cavalry officer named Benjamin Tallmadge as the head of his “Secret Service”, with the mission of establishing sources of intelligence information in New York. Tallmadge began by recruiting two of his own childhood friends, people he could trust completely. One was a whaling captain named Caleb Brewster, and the other was a farmer named Abraham Woodhull. To protect their identities from the British, they used code names: Tallmadge was known as “John Bolton”, and Woodhull reported to him using the name “Samuel Culper”. Shortly later, Woodhull recruited a friend of his named Robert Townsend, a New York society columnist and merchant with connections in the British Army, who was given the code name “Sam Culper Jr”. Another source of information was Hercules Mulligan, a friend of Alexander Hamilton who owned a clothing store and who was married to the daughter of a British Admiral.
Together the spy ring was known as “the Culper Group”. The group grew over time with the addition of more sources and couriers. Its operations were so secretive that not even Washington knew who was involved. To protect themselves, the group’s members all used code names, and passed all their messages in encrypted ciphers, using invisible ink. They also passed information using “dead drops”–secret locations where they would leave messages to be picked up later by other contacts–and by special coded messages published in innocuous-sounding newspaper announcements.
Brewster, Townsend, and the other sources would gather information on British movements and pass it on to Woodhull. Woodhull would then pass the information to contacts in Connecticut, using local tavern-keeper Austin Roe as a courier. Another member of the group was Anna Smith Strong, Woodhull’s neighbor whose husband had been imprisoned by the British. She would use a particular arrangement of laundry on her clothesline to signal meetings between Woodhull and his contacts.
At first, the Culper ring, through Townsend and Woodhull, had good information about the British Army, but not much about the Navy. But Woodhull soon recruited a local society woman who had extensive connections among British Navy officers, and who began regularly passing information back to Woodhull. To this day, this woman, referred to only by the code number “355”, remains unidentified. Most historians suspect she was the wife of a British Navy officer. The Culper group also had several contacts close to General John Andre, the head of British counter-intelligence. One of these was an unknown aide of Andre’s, who would inform the spy network whenever the British began to suspect one of them. Andre, an eligible bachelor, was also surrounded by young society ladies from New York–several of whom were passing information to Woodhull.
Throughout the war, the Culper network passed on valuable information to Washington concerning British plans and troop movements. In 1777, the spy group was able to warn Washington of a British battle plan to surround him at White Marsh, and in 1780, the group informed Washington that the British were planning to ambush the French Army (France had just decided to begin aiding the rebellion) when it arrived in Rhode Island, allowing the potential disaster to be avoided.
The Culper group’s biggest intelligence coup of the war, however, centered around the fortress at West Point. While the British controlled Long Island and Manhattan, the colonial cannon batteries at West Point controlled access to the Hudson River Valley. If the British could capture West Point and send their naval forces into the river, they could split the colonies in half and gain a major strategic advantage–and the British found their opportunity when the American commander of West Point, General Benedict Arnold, secretly contacted them in 1779. Arnold had been one of Washington’s most successful generals, winning the crucial battle at Saratoga, but when he was passed over for a promotion he became resentful, and offered to turn over the West Point fortress to the British in exchange for a military commission in the English Army. The Culper network was able to find out about the plan before it was put into effect and notified Washington. Arnold escaped to the British, was made an officer, and earned scorn as America’s most famous traitor. Arnold’s British contact was none other than John Andre, the British intelligence chief, who was captured in civilian clothing traveling to meet Arnold and was searched, uncovering detailed maps of West Point hidden in his boot. Andre was hanged as a spy.
With Andre’s arrest and execution, however, the Culper spy ring seems to have lost its primary sources of information. And after Arnold joined the British, he began searching to find the spies who had discovered his plans to defect. Woodhull and Townsend fell under suspicion, and ended their spy activities. But from 1778 to 1780, the Culper Spy Ring was the most successful intelligence operation on either side during the American Revolution.