By 1779, however, Mathews recovered was granted a limited parole and permitted to live in New York City. He wrote to Governor Thomas Jefferson and to the Continental Congress urging a prisoner exchange. Jefferson wrote to Mathews to explain his decision to leave him in New York City as a parolee and instead exchange for others still suffering in much worse conditions on the prison ships. Mathews turned his attention toward the improvement of living conditions for fellow prisoners of war, securing money and provisions for this aim from Congress and the State of Virginia. He was formally exchanged on December 5, 1781, at which point he was given command of the 3rd Virginia Regiment and went with Major General Nathaniel Greene into the southern theater, though he saw no further action in the war. Mathews was brevetted brigadier general at the end of the war; on September 30, 1783, Congress conferred a "general brevet" on the officers Continental Army, advancing all below the rank of major general by one rank. Mathews was an Original Member of the Society of the Cincinnati.