In order to play these free DLC missions, you’ll need to first complete the story and then reach world tier 5 by completing all invaded missions. When you’ve reached world tier 5, go to your map and fast travel to them or see the pilot at the Whitehouse. For this particular episode you’ll need to start “The Pentagon” mission at the bottom of the map. It consists of two main missions that each unlock their own achievement and can be done in two sittings.