From 2000 to 2005 he starred in The Patriot , Monster 's Ball , A Knight 's Tale , The Four Feathers , Ned Kelly , The Order , and The Brothers Grimm . From 2000 to 2005 , he starred in supporting roles as Gabriel Martin , the eldest son of Benjamin Martin ( Mel Gibson ) , in The Patriot ( 2000 ) , and as Sonny Grotowski , the son of Hank Grotowski ( Billy Bob Thornton ) , in Monster 's Ball ( 2000 ) ; and in leading or title roles in A Knight 's Tale ( 2001 ) , The Four Feathers ( 2002 ) , The Order ( 2003 ) , Ned Kelly ( 2003 ) , Casanova ( 2005 ) , The Brothers Grimm ( 2005 ) , and Lords of Dogtown ( 2005 ) .