Benjamin Thompson Letter to [?], May 6, 1775. Thomas Gage Papers.
Benjamin Thompson, one of the earliest and most famous American scientists, did not believe in the American rebellion. In this letter, Thompson did not hide his leanings towards the loyalist cause, but he did use invisible ink to include secret text within the body of his letter. The secret letter is proof of Thompson’s previously suspected intelligence work for the British Army. Thompson wrote this letter from Woburn, Massachusetts because he had been run out of his hometown in New Hampshire for sending British deserters back to Gage’s headquarters in Boston. In the beginning of the letter, Thompson briefly mentioned the Battle of Lexington and Concord that had happened two weeks prior, stating that Gage has “already better intelligence of them affairs than I am able to give.” Instead he concentrated on explaining the movements of the “Rebel Army (if that mass of confusion may be called an Army).”
Within the visible text of the letter, Thompson reported on the actions of the Continental Congress’ resolution to raise 30,000 men against the British which he had learned from a member of the Provincial Congress of Massachusetts, possibly Benjamin Church. He also detailed the Rebel Army’s plan to attack the “Castle,” or the Castle William Fort at Castle Rock. Instead the Continental Army, led by Ethan Allen and Benedict Arnold, attacked Fort Ticonderoga in Lake Champlain. In invisible ink Thompson wrote of a secret cache of papers, unfortunately the name of the courier has been erased and nothing is known of the Thompson’s papers. In October 1775, around the same time Benjamin Church was tried for treason by Washington, Thompson left Boston and returned home to New Hampshire to his wife for a short time. On November 4, 1775, Thompson was back in Boston writing a detailed report on the conditions in the American camp for Sir William Howe, General Gage’s replacement. In March of 1776, when Howe evacuated Boston, Thompson sailed to England to assist Lord George Germain who ran the British troops from England. Thompson failed to notify his wife and small daughter in Concord, New Hampshire of his plans and they never saw him again.