After resigning from the army in a dispute over seniority, Oswald returned to a career in publishing and journalism. Over the next decade he published newspapers in Baltimore, Philadelphia, and New York. In 1792 he went to France where he joined the French Revolution and assumed command of an artillery unit as colonel. After fighting at Jemappes he went on a secret mission to Ireland. He returned to New York in 1795 and died in an outbreak of Yellow Fever.