If you find yourself in a trench in your dream, this may express your fear that a current situation is not as secure as you might think. A trench may also be warning against inflexibility and entrenched views. To see or live in a concentration camp in your dream indicates that you are afraid of differences; you are having difficulties accepting others and the way in which they are different from you.
Learn to appreciate diversity and the uniqueness in yourself and in others around you.
If you actually lived in a concentration camp, the dream may signify a situation in your waking life which is triggering similar feelings.