Since this military service ends only at death...

Referring to the Christian's spiritual battle against Satan and the devils, Calvin says:

"We must, then, bend our every effort to this goal: that we should not let ourselves be overwhelmed by carelessness or faintheartedness, but on the contrary, with courage rekindled stand our ground in combat. Since this military service ends only at death, let us urge ourselves to perseverance. Indeed, conscious of our weakness and ignorance, let us especially call upon God's help, relying upon him alone in whatever we attempt, since it is he alone who can supply us with counsel and strength, courage and armor. (Calvin, Institutes I. xiv. Section 13, bold mine)"