John Jay to Philip Schuyler - Insecurity of Communication and Schuyler's Resignation, March 21, 1779

Secret communications and spy networks were a very important part of the process of intelligence-gathering during the Revolutionary War. Coded letters and spies often conveyed information that was pivotal to the outcomes of individual battles and the whole war itself. These documents show some of the ways in which officers were able to gather and communicate information secretly, as well as prevent the enemy from communicating intelligence.
General Philip Schuyler was a member of a notable early Albany, NY family. He was appointed a Continental Army Major General in 1775 by the Continental Congress, but was quickly replaced in 1777. In 1779 he resigned from the army.  He joined the Continental Congress, first serving as a NY State Senator (1780), then as a U.S. Senator for NY (1788).