The system was remarkably simple. Every Tuesday evening, detailed reports of what had transpired in Ben Franklin's French household made their way, in invisible ink, to the southern perimeter of the Tuileries Gardens. There the missives were stuffed into a bottle and lowered by string into a deep hollow at the foot of a tree. After dark the British ambassador's secretary fished them out to be dispatched to London and deposited his side of the correspondence under a neighboring boxwood.
Franklin was encircled by spies from the minute he set foot in Paris to solicit support for the Revolutionary War. On all minds the burning question was whether France intended to assist the rebel colonies, and if so, when and how it would do so. The French monarchy had its own efficient news service in thousands of paid informants who reported from their favorite cafés, their mistresses' boudoirs, their medical rounds, their hotel desks, to police chief Jean-Charles Lenoir. Among Lenoir's roundups was a weekly catalog of the city's sexual escapades. This was a city of which it was said that when two Parisians talked, a third inevitably listened. Lenoir was among the first to trail the celebrated American on his arrival, sounding a note of uneasiness about his potent celebrity. The chief had serious competition: Lord Stormont, the British ambassador in Paris, pledged to observe the "veteran of mischief" as closely and as inconspicuously as he could. As that was not easy for an accredited ambassador, British intelligence stepped in.
The British agents reported to an immensely gifted master spy who spoke better French than most Parisians and whom even Lenoir's men found difficult to shadow. America might claim some credit for Paul Wentworth's spectacular performance: he was a New Hampshire native. His agents were a varied but inventive bunch, filching diaries and diving into closets. They proved recklessly unable to resist Paris' charms. One agent, as fond of back stairways as of disreputable addresses, never left Paris without attending a drunken orgy. In the course of one such evening, he entrusted his confidential documents to a more sober reveler, who saw that they made their way to Versailles.
Franklin knew himself to be the object of what he aptly termed "violent curiosities" but at home insisted that he had no intention of speaking other than the truth or of implementing any particular security precautions or even of dismissing his valet if he were "a spy, as probably he is." Against all counsel, he stayed his course; he reasoned in part that the quantity of information in itself provided a kind of smoke screen. His apathy about security came at a price. Armed with detailed inventories of French munitions bound for America, the British were repeatedly able to confront the French with evidence of this collusion.
Meanwhile, the weekly white-ink dispatches arrived like clockwork in London, where, moistened with a chemical solution, their hidden messages appeared in red. And the source? Decades after his death, he was revealed to have been a perfectly loyal servant of both sides. The consummate double agent was the brilliant Edward Bancroft, Franklin's secretary and one man who had had his confidence all along.