Dave, I believe thew final battle depicted in THE PATRIOT was an amalgam of both Cowpens and Guildford Courthouse.
As for British atrocities, Tarleton's Quarter and indiscriminate brutality against all civilians were the most significant factors for why ppl in the South became more motivated to fight Cornwallis. And there were also instances of British atrocities in other theatres of the ARW, such as the night bayonet attack of British grenadiers at Paoli tavern, Pennsylvania in 1777 where no prisoners were taken, and the depradations in NY and NJ of the likes of Col. James DeLancey's loyalist Westchester Light Horse Bn irregulars, who came to be known as 'Cowboys'.