Good deal of graphic violence set in the American Civil War, including people being killed by cannon blasts and gunfire. Also depicts cities being burned and slaves in chains. None of this is in Shakespeare's play.
Also includes supernatural violence with the Prospero-like character creating storms and casting spells to try and vanquish his enemies.
The very opening scene depicts a great deal of violence. There is an attempted lynching, followed by the shooting of an African-American couple by the KKK. The man is not killed (though he is covered in blood). The woman, however, is shown being shot in the head and her blood and brains splatter against the wall in graphic detail.
We see numerous Union soldiers severely injured, covered in blood and bandages. We see an amputation taking place with very bloody detail.
Extremely strong violence for a PG-13 movie.