Isabella, Mortimer Junior, Kent, Prince Edward, and Sir John arrive in England. Isabella laments the necessity of civil wars that force “kin and countrymen [to] / Slaughter themselves in others,” and begins to describe how Edward II's irresponsibility as a king has brought them to this impasse.
Isabella describes civil war as self-destructive in the most literal sense: killing one's kin and countrymen, she says, is the same as killing oneself. This once again speaks to the dangers of internal discord, while echoing the language Edward has earlier used to describe his mental state in the wake of Gaveston's exile (when he felt "divided from himself"). In this way, the play establishes a parallel between the inner turmoil of England's monarch and the inner turmoil of England itself, implying that the former has brought about the latter. Isabella's description of Edward as "misgoverned" reinforces this connection, because it implies that Edward has failed to govern himself in much the same way he has failed to govern the country.
Mortimer Junior interrupts Isabella and tells her that she must be less “passionate” in speech if she wants to be a “warrior.” He then briefly states their loyalty to Prince Edward and reiterates that their purpose in fighting is to restore order to the country. Sir John orders the trumpets to sound, and the group leaves for battle.
The tension between language and violence is particularly clear in this exchange. As Isabella speaks about Edward's failures as a king, she appears to grow angrier (or, as Mortimer says, more "passionate"). However, just as she prepares to launch into a detailed explanation of a king's responsibilities to his people, Mortimer cuts her off midsentence with a warning that flowery speeches do not suit "warriors." His own explanation of why the rebels are going to war is brief and matter-of-fact, presumably so that they can get down to fighting sooner. Mortimer always favors action over language.