When Benjamin Martin brought Cornwallis his dogs....
They had a rather civilized exchange at Cornwallis's desk. That would have been an ideal time for Martin to tell Cornwallis about the war atrocities committed by Tavington, (including killing Martin's son....when all his family was doing at the homestead was providing aid and medical attention to any solders (on either side) that needed it).
It seems like Cornwallis would have been sympathetic to Martin, and would bring disciplinary measures on Tavington.