Scholars think that high-ranking British officers would talk freely about troop placements around Agent 355 because she was a woman and entirely underestimated her presence, essentially making her invisible, but always putting her in the room where it happens.
General Washington, along with Major Benjamin Tallmadge, founded the Culper Ring, a ring of spies that was tasked to provide him with information on the British Army’s operations in New York City, the Loyalists’ headquarters. It’s members were most active between October of 1778 and the British evacuation of New York in 1783.
While we’re talking about anonymity equaling a good spy, it’s important to note that the existence of the Culper Ring was not even known by the general public until the 1930s. That means, the Culper Ring Patriot spies were so adept at their espionage that they remained mostly anonymous for 150 years…
https://www.messynessychic.com/2021/09/23/who-was-agent-355-the-mystery-of-americas-first-female-spy/