Halteese is a country which was once held under that of a Monarchy. Furthermore, Hyle explains to his subordinate that Halteese has recently become a country which exercises Democracy, alas, hardly a thing has changed at the countries very root. Beyond that, not much else is known about Halteese with the exception that Halteese has been locked in a long and bitter war with Dalkia.
It is within the winter months when the Cadet/Player reaches the outskirts of Halteese and are only ordered penetrate and secure a route to Halteese's capital; once that is done, the player's forces are to await the Main Army and support them as a rear.
Halteese has been waging war with Dalkia for years and it seemed that, at least for a time, a peace had been in between the two. That is until Aurelia reinstated the bloodshed between the two countries.
At some point and for an unknown reason, Halteese attacks Grandall--which it is then that Strife orders the Player to attack Halteese albeit a suicide mission.
Demuth was the youngest of three brothers with (Halphas and possibly Yufeng) to be his elder brothers. Demuth ordered the attack upon his homeland so that he could expand his own kingdom--which was given to him after an arragement was made. This arrangement left only two brothers whom were in pursuit of the throne after Demuth left.