[2] At the beginning of the conflicts with the mother country, he espoused the cause of the colonies, and was a signer of the non-importation agreement of the citizens of Philadelphia in 1765.
He presided at the meeting of the mechanics and tradesmen of the city held on June 9, 1774, to consider a letter from the artificers of New York, and was a member of the committee to reply to the same.
On September 16, 1775, he was appointed muster-master of the Pennsylvania navy, which office he resigned, February 23, 1776, to concentrate on his commercial affairs.
This necessitated the establishment of agencies in Nantes and Paris, and Ross made several visits to France during the war.
He was on familiar terms with George Washington, Benjamin Franklin, and Robert Morris, and several entries in General Washington's diary, during the sittings of the convention to frame the United States Constitution, tell of engagements to dine with Mr. Ross at his country place, Grange Farm or the Grange, named after the home of Lafayette.