The legend of “Agent 355” originates in a single passing reference made in a letter written by Abraham Woodhull. Woodhull was one of the leading members of the Culper Ring, a network of spies founded during the Revolutionary War at the instigation of George Washington, at that time the Commander of the Continental Army. Their task was to sniff out information about the activities of the British occupying forces in New York and pass it on to Washington through a trusted chain of agents. 

Many letters written by members of the Culper Ring survive, giving a fascinating and detailed account of how intelligence operations were carried out 18th-century-style, making use of invisible ink, complicated codes and the like. 

Woodhull was given the codename Samuel Culper, while his colleague Robert Townsend – a society journalist whose access to New York’s beau monde helped him accrue information – was designated as Samuel Culper Jr. (Washington himself chose the names, probably in sentimental reference to Culpeper County, where he had worked as a surveyor in his youth.)

The members of the ring also used numbers to stand in for certain words in their missives, and eventually they were given codebooks containing more than 700 words and their numerical stand-ins (so instead of writing about, say, “a murder”, they would refer to “a 387”). They also gave each other numerical designations: Major Benjamin Talmadge, who ran the network on Washington’s behalf, was 721, Woodhull was 722, Townsend was 723, and so on. 

Enter “Agent” 355. Writing to Talmadge about his plans to gather intelligence on the British in a letter dated August 15 1779, Woodhull (who lived on a farm on Long Island) wrote: “I intend to visit New York … and think by the assistance of a 355 of my acquaintance, I shall be able to outwit them all.” In the Culper codebook, 355 signifies “lady”. 

There we have it: “a lady” assisting Woodhull in collecting intel – one of the earliest recorded female spies in Western history. Or do we? 

The notion of “Agent 355” did not enter the public consciousness until the 1930s and could be said to be a creation of the historian Morton Pennypacker. Pennypacker examined and deciphered a newly discovered cache of the Culper Ring letters, including the 355 letter, and published his conclusions in his book General Washington’s Spies in 1939. 

The little word “a” plays an important role here. Although Woodhull’s letter referred to “the assistance of a 355” – i.e. of “a lady” – Pennypacker, ignoring the indefinite article, read it as “the assistance of 355” and declared that 355 must be the numerical designation of a female Culper agent. This theory seems even more suspect when you note that the three-digit designations of the many other Culper agents all began with a “7”.

Nevertheless Pennypacker has inspired many other writers to place 355 at the heart of the Culper Ring, among them Brian Kilmeade (a well-known Fox News host) and Don Yaeger in their recent US bestseller George Washington’s Secret Six (2013). 

Kilmeade and Yaeger, consulting the Culper codebook, emphasise that the number 355 denotes “lady” as opposed to “woman”, which is designated by 701: therefore, “her code indicates that she was of some degree of social prominence”. On this basis the authors assert that while “Townsend gathered information from soldiers around the city and sailors at the dock, Agent 355 charmed strategic details out of high-ranking officers at soirees”. 

However, the historian Alexander Rose, author of Washington’s Spies: The Story of America’s First Spy Ring, is sceptical of claims that the “lady” was a full-blown Culper agent. “Put very simply, there was no ‘Agent 355’,” he tells me.

Woodhull’s words are often taken out of context, Rose argues. Woodhull was writing to Talmadge about his fear of being subjected to a random search by British troops while he was carrying sensitive material; if he was accompanied by a woman, however, he was less likely to be targeted – “a couple would raise fewer suspicions than a man traveling alone”, says Rose. So we can assume that this particular 355 was a friend of Woodhull’s who supported the Loyalist cause, but it’s a stretch to assume that she was a full Agent of the Culper Ring.