A disintegrating armed force already finds it extremely difficult to consolidate its fighting capacity; in this digital age, without the support of a core intelligence system, roaming the active Devil Forest is akin to wandering aimlessly like a blind person.
What awaits the soldiers is not extinction but rather the possibility to disembark from their Mechas and utilize their wilderness survival skills. Those fortunate may survive until the end of the war and be repatriated or slip into a nearby city undiscovered and take a covert ship back to their homeland, although this probability is very low.