The commander of the Serbian Army sent with orders of "fighting until the last man" in order to buy time for a victory in the south against the Hellenic Army was more or less committing treason. His objective was to negotiate a peaceful surrender with the Germans, not only for his own men, but for all of Serbia.
He knew he wasn't exactly in a position to do so, and he also knew that Serbia, or more specifically its royal family in conjunction with the Black Hand, was guilty of a great many crimes. Crimes against not only the Habsburgs, but Bruno personally, as well as many innocent people in the Balkans.
At the end of the day, there was nothing he could really do to make amends for these sins. All he could do was ask for more peaceable terms than total annihilation by giving the enemy a show of good behavior.
