By December of 1776 New Jersey was under the control of Lord Cornwallis and his Hessian troops. John Hart had a price on his head, living or dead, and it was then that he was forced into hiding. Moving from house to house among his friends or retreating into the Sourland Mountains, believed to have hidden in a rock formation known as the Rock House (see picture of marker), and was constantly on guard against the Hessian scouts. His children were scattered around the country seeking safety.
John Hart returned home after the Washington’s Army defeated the British at the battle of Trenton in December 26th, 1776 and Princeton, January 3rd, 1777. He continued in this office through annual elections until the first sessions in 1778 when he was forced to retire because of ill health. John Hart gave up his public life at that time. He passed away May 11th, 1779. John Hart did not live to see the triumph of his cause which would come with the surrender of Lord Cornwallis at Yorktown, Virginia on October 19th, 1781, and the treaty of peace on February 3,