The Spymaster's Toolkit

February 14, 2016

Innovation and Technology

Long before General William Donovan recruited spies to advance the American war efforts during World War II as Director of the Office of Strategic Services (OSS), predecessor to the CIA, General George Washington mastered the art of intelligence as Commander of the Continental Army during the Revolutionary War.

Washington was a skilled manager of intelligence. He utilized agents behind enemy lines, recruited both Tory and Patriot sources, interrogated travelers for intelligence information, and launched scores of agents on both intelligence and counterintelligence missions. He was adept at deception operations and tradecraft and was a skilled propagandist. He also practiced sound operational security. Washington fully understood the value of accurate intelligence, employing many of the same techniques later used by the OSS and CIA.

As we celebrate the birthday of the first American President, we wanted to highlight some of the tradecraft employed by Washington and his contemporaries to secure our independence from the British and offer insights on its use today. Were it not for the use of secret writing, concealment devices, propaganda, and intercepted communications, there may have been a very different outcome to the War of Independence.

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Secret Writing

Revolutionary War: American agents serving abroad composed their intelligence reports using invisible ink. George Washington believed this would “not only render his communications less exposed to detection, but relieve the fears of such persons as may be entrusted in its conveyance.”

Communicating via invisible ink required the use of several chemical compositions. One mixture was used to write with disappearing ink, the other mixture was applied to the report to make it legible. Despite their invisible communications, it is estimated that the British intercepted and decrypted over half of America’s secret correspondence during the war.

CIA: The CIA has declassified several documents that provided recipes for making invisible ink. One recipe instructs: “Take a weak solution of starch, tinged with a little tincture of iodine. This bluish writing will soon fade away.” A mixture for exposing secret writing included “iodate of potassium, 5 grams, with 100 grams of water, and 2 grams of tartaric acid added” but warned, “run a hot iron over the surface being careful not to scorch the paper.”

During the Cold War, a major advancement in secret writing technology was the shift from liquid invisible inks to dry systems. The KGB was one of the first foreign intelligence services to employ a dry method. The CIA’s Office of Technical Services in the Directorate of Science and Technology spent considerable time researching Soviet systems and finally succeeded not only in “breaking” them, but in anticipating where its KGB counterpart would go next in the never-ending search for more secure systems. By the end of the Cold War, a kind of tacit convergence had emerged as both sides applied new techniques that used very small, almost undetectable quantities of chemical in secret writing messages. In the words of one CIA chemist, it was like “uniformly spreading a spoonful of sugar over an acre of land.”

Concealment Devices

Revolutionary War: Agents used a variety of modified objects to conceal their secret messages. One device was a wafer-thin lead container that would sink in water, or melt in fire, thus destroying its contents. The device was small enough that an agent could swallow it if no other means of discarding were available. This was done as a last resort as ingestion was typically followed by a severe bout of lead poisoning. The lead container was eventually replaced by a silver, bullet-shaped container that could be unscrewed to hold a message and which would not poison a courier who might be forced to swallow it.

CIA: A concealment device can be any object used to clandestinely hide things. They are typically ordinary, every-day objects that have been hollowed out. The best concealment devices are ones that blend in with their surroundings and call no attention to themselves. They can be used to hide messages, documents, or film. Some examples of concealment devices include hollowed out coins, dead-drop spikes, shaving brushes, and makeup compacts.


Revolutionary War: During the American Revolution, the British had a shortage of soldiers so they hired almost 30,000 German Hessian auxiliary forces to fight against the Americans. The Continental Congress devised a propaganda campaign to encourage the Hessian mercenaries to defect to America. The campaign included offering land grants to those mercenaries fighting for the British on American soil. The offers were written in German on leaflets disguised as tobacco packets. A mock-defector ran through the mercenaries’ camps encouraging others to defect as well. As part of the campaign, Benjamin Franklin forged a letter to the commander of the Hessians, “signed” by a German prince. The letter instructed the commander to let the wounded mercenaries die. This dealt a blow to the morale of the Hessians. Between 5,000 and 6,000 Hessian mercenaries deserted from the British, in part because of American propaganda.

CIA: Propaganda campaigns use communication to alter a population’s beliefs and views thus influencing their behavior. There are three types of propaganda: white, black, and grey. White propaganda openly identifies the source and uses gentle persuasion and public relations techniques to achieve a desired outcome. For example, during the Persian Gulf War, the CIA airdropped leaflets before some Allied bombing runs to allow civilians time to evacuate and encourage military units to surrender. Black propaganda, on the other hand, is misinformation that identifies itself with one side of a conflict, but is truly produced by the opposing side — like Franklin sending the letter “from” a German prince. Grey propaganda is the most mysterious of all because the source of the propaganda is never identified.

Intercepted Communications

Revolutionary War: The Continental Congress regularly received quantities of intercepted British mail. General Washington proposed to “contrive a means of opening them without breaking the seals, take copies of the contents, and then let them go on. By these means we should become masters of the whole plot.”

CIA: Clandestinely opening, reading and resealing envelopes or packages without the recipient’s knowledge requires practice. Flaps and seals’ opening kits were used in the 1960s. A beginner’s kit offered the basic tools for surreptitious opening of letters and packages. Once mastered, an advanced kit with additional tools was used. Many of the tools were handmade of ivory and housed in a travel roll.

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Washington employed the use of many other intelligence gathering techniques still in use today to secure our independence and freedom from Great Britain. Not only is he The Father of His Country, but he is heralded as a great spymaster. Upon the conclusion of the Revolutionary War, a defeated British intelligence officer is quoted as saying, “Washington did not really outfight the British. He simply out-spied us.”

Related Stories

Intelligence in the War of Independence
Julia Child: Cooking Up Spy Ops for OSS
Nathan Hale: American Patriot. Army Ranger. Spy.

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