George Washington, Spymaster: He Urgently Requests More Invisible Ink From Its Inventor, James Jay, In the Handwritten Letter That Led to the Creation of the Famous Secret Laboratory That Supplied the Culper Spy Ring

Invisible ink was Washington’s most effective espionage tool in the Revolutionary War, and he was anxious to maintain a supply; A search of public sale records going back 40 years shows no Washington letters to Jay or about invisible ink whatever having reached that marketplace

“The liquid with which you were so obliging as to furnish me for the purpose of private correspondence is exhausted; and as I have found it very useful, I take the liberty to request you will favour me with a further supply…Should you not have by you the necessary ingredients, if they are to be procured at any of the Hospitals within your reach, I would wish you to apply for them in my name.”

Spycraft was of one Gen. George Washington’s highest priorities during the American Revolution. He used it to acquire key intelligence about British troop movements, supplies, and battle plans, and to communicate his own instructions and orders to both his spy network and his officers who are operating at a distance. Because such intelligence and instructions could not be overtly communicated to him, or sent from him, without placing his agents at great risk, or revealing his own plans, Washington sought a secure method of communication. Hiding letters was one option, but as Major Andre discovered to his sorrow in the Benedict Arnold affair, hidden letters can be found. Ciphers and secret codes were another option, and were used to ensure that the contents of a letter could not be understood if correspondence was captured. In ciphers, letters were used to represent and replace other letters to mask the true message of the missive. The letter’s recipient utilized a key to decode the document’s true message. But this too had its limitations, as is made manifest by Washington’s inability to communicate with Lafayette in 1781 because Lafayette lacked the cipher.

A method favored by Washington was use of invisible ink. Rudimentary forms of this existed before the Revolution. But Washington wanted something more, an ink that could only be revealed by a unique, specially formulated reagent. Sir James Jay answered the general’s call. Jay, brother of American patriot and Continental Congress member John Jay, was a physician that dabbled in chemistry. He created a chemical solution out of tannic acid that was a superior form of invisible ink, which he supplied to Washington. Washington would then pass it on to the Continental Army’s spymaster, Major Benjamin Tallmadge who in turn provided it to others in his network.

This was the spy ink of the Revolutionary War.

To avoid suspicion, Washington instructed his spies to write seemingly banal letters and insert their secret messages between the lines; these secret messages could only be discerned by treating the letter with heat or a chemical substance. The recipient placed the paper over the flame of a candle or treated it with a chemical reagent, such as sodium carbonate, which would reveal the letter’s hidden contents. Washington himself instructed his agents in the use of what was referred to as the “sympathetic stain,” noting that the ink “will not only render. . .communications less exposed to detection, but relieve the fears of such persons as may be entrusted in its conveyance.” Washington suggested that reports could be written in the invisible ink “on the blank leaves of a pamphlet. . . a common pocket book, or on the blank leaves at each end of registers, almanacks, or any publication or book of small value.”

Jay supplied Washington, but avoid detection and because he worked with scarce ingredients, Jay was able to produce only small quantities of the ink. Washington wanted more ink to prevent damaging leaks of information. One unfortunate incident occurred when the British captured letters exchanged by Washington and his spy Benjamin Tallmadge in July 1779. Neither Washington nor Tallmadge had used codes or ink. Their lack of secrecy cost Washington dearly: his spy George Higday was taken prisoner, and the British moved closer to discovering the Culper Ring in New York. This episode, among others, increased Washington’s drive for a greater use of invisible ink.

The Culper Spy Ring was an American spy network operating during the War of American Independence that provided George Washington with information on British troop movements. In November 1778, George Washington appointed Major Benjamin Tallmadge as director of military intelligence, charged with creating a spy ring in New York City, the site of British headquarters.  This network became known as the Culper Spy Ring and operated successfully in and around New York City for five years, during which time no spy was ever unmasked.

Autograph letter signed, Headquarters, Morristown, April 9th, 1780, to Jay, urgently requesting more invisible ink. “Dear Sir, The liquid with which you were so obliging as to furnish me for the purpose of private correspondence is exhausted; and as I have found it very useful, I take the liberty to request you will favour me with a further supply. I have still a sufficiency of the materials for the counterparts on hand. Should you not have by you the necessary ingredients, if they are to be procured at any of the Hospitals within your reach, I would wish you to apply for them in my name. I hope you will excuse the trouble I give you on this occasion. With great regard, I am, Dr Sir, Yr Most obed Servt, Go. Washington.” He adds a PS: “If you should not be able to prepare the liquid in time for the bearer to bring, & will be so good as to commit it to the care of Colo. Hay, he will forward it to me.”

Jay replied just a few days later.  He sent the small amount he had left and made a plea to Washington: “The composition requires some assistance from Chemistry; & our house is so small, & so well inhabited, that there is not a corner left where a little brick furnace, which a Mason could build in two hours time, can be placed.”  Jay wanted a laboratory built for his work.  And Washington obliged, creating one at Fishkill.  This was the first secret spy laboratory in the United States.

This is an extremely rare letter of Washington related to wartime espionage, and an uncommon war date ALS. But in a real sense it is unique. A search of public records going back 40 years reveals no letters of Washington mentioning invisible ink or written to Sir James Jay have reached that marketplace, nor can we recall ever having seen any. Obtained by us privately, it has not been on the market for at least a century.