British. In 1781, James Lovell, who designed cipher systems used by several prominent Americans, determined the encryption method that British commanders used to communicate with each other. When a dispatch from Lord Cornwallis in Yorktown, Virginia, to General Henry Clinton in New York was intercepted, Lovell's cryptanalysis enabled Washington to gauge how desperate Cornwallis's situation was and to time his attack on the British lines. Soon after, another decrypt by Lovell provided a warning to the French fleet off Yorktown that a British relief expedition was approaching. The French scared off the British flotilla, sealing the victory for the Americans. Intercepting communications The Continental Congress regularly received quantities of intercepted British and Tory mail. On November 20, 1775, it received some intercepted letters from Cork, Ireland, and appointed a committee made up of John Adams, Benjamin Franklin, Thomas Johnson, Robert Livingston, Edward Rutledge, James Wilson and George Wythe "to select such parts of them as may be proper to publish." The Congress later ordered a thousand copies of the portions selected by the committee to be printed and distributed. A month later, when another batch of intercepted mail was received, a second committee was appointed to examine it. Based on its report, Congress resolved that "the contents of the intercepted letters this day read, and the steps which Congress may take in consequence of said intelligence thereby given, be kept secret until further orders." By early 1776, abuses were noted in the practice, and Congress resolved that only the councils or committees of the safety of each colony, and their designees, could henceforth open the mail or detain any letters from the post. When Moses Harris reported that the British had recruited him as a courier for their Secret Service, General Washington proposed that General Schuyler "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." From that point on, Washington was privy to British intelligence pouches between New York and Canada. Technology Dr. James Jay used the advanced technology of his time in creating the invaluable "sympathetic stain" used for secret communications. Perhaps the American Patriots' most advanced application of technology was in David Bushnell's Turtle, a one-man submarine created for affixing watchword-timed explosive charges to the bottoms of enemy ships. The "turtle," now credited with being