When you break down the word "sacrifice," the first part, "sacr," means sacred or holy. Sacrifice implies a set of beliefs for which one is willing to give something up to achieve. In All Quiet on the Western Front, the men sacrifice everything for nothing. They give up their lives for a set of ideals that are either incomprehensible or false. The fact that they sacrifice for unknown reasons gives rise to great and widespread tension.
The soldiers do not know why they are sacrificing their lives.
The soldiers give up their lives for one another.