Varick served as secretary to General Philip Schuyler followed by a term as Benedict Arnold's aide-de-camp where he became unknowingly emeshed in Benedict Arnold's treason. He was rescued by George Washington who appointed him to be his recording secretary which he did for the remainder of the war. His heroic effort in organizing what grew into 44 bound volumes of Washington's war papers. “I am fully convinced,” Washington wrote to Varick on 1 Jan. 1784, “that neither the present age or posterity will consider the time and labour which have been employed in accomplishing it, unprofitably spent”. After the war, he returned to New York and served as the city's Recorder was speaker of the New York State Assembly and the state attorney general.