The Greil Army, is a group of soldiers, traveling to the Tower of Guidance in Begnion, in part 4 of Radiant Dawn. The commander of the group is Ike. As such, he can't be removed from this group. He is joined by Soren and Titania. The rest of the Greil Mercenaries, however, may be assigned to a different group. Queen Nailah, Prince Rafiel, Prince Kurthnaga, and Ena also join them. (Though Kurthnaga and Ena do not fight until they reach the tower) Whether some units are in the group or not, can be chosen by the player.
Throughout the course of their march, they encounter a Begnion falcon knight, Catalena, and former duke of Tanas, Oliver. This army appears in chapters, 4-1, 4-4, and Rebirth(1). These units can enter the Tower of Guidance at the endgame.