In this essay, Lewis makes a very compelling case for his conclusion that he cannot endorse pacifism, either through rational argument or appeal to the Bible. Without quoting the whole essay here, I cannot hope to do it justice, so that's not my purpose. I encourage you to read it yourself.*
To Lewis, the evidence against pacifism is--once he has undertaken the exercise of looking into it--so overwhelming that he wonders why he even questioned it in the first place. He suspects, in retrospect, that there was a strong ulterior motive for wishing his researches might have led to an opposite conclusion. And in discussing this aspect of the issue, he details the misery of the soldier's life in a very insightful passage. This, I guess, is what I particularly wanted to share, as many of us currently have friends, family, or neighbors going through the adversity of a soldier's life that Lewis so well identifies. Remember, Lewis was speaking to a group of pacifists in the early years of WWII.
It remains to inquire whether, if I still remain a Pacifist, I ought to suspect the secret influence of any passion. I hope you will not misunderstand me. I do not intend to join in any of the jibes to which those of your persuasion are exposed in the popular press. Let me say at the outset that I think it unlikely there is anyone present less courageous than myself. But let me also say that there is no man alive so virtuous that he need feel himself insulted at being asked to consider the possibility of a warping passion when the choice is one between so much happiness and so much misery. For let us make no mistake. All that we fear from all the kinds of adversity, severally, is collected together in the life of a soldier on active service. Like sickness, it threatens pain and death. Like poverty, it threatens ill lodging, cold, heat, thirst, and hunger. Like slavery, it threatens toil, humiliation, injustice, and arbitrary rule. Like exile, it seperates you from all you love. Like the gallies, it imprisons you at close quarters with uncongenial companions. It threatens every temporal evil--every evil except dishonour and final perdition, and those who bear it like it no better than you would like it. On the other side, though it may not be your fault, it is certainly a fact that Pacifism threatens you with almost nothing. Some public opprobrium, yes, from people whose opinion you discount and whose society you do not frequent, soon recompensed by the warm mutual approval which exists, inevitably, in any minority group. For the rest it offers you a continuance of the life you know and love, among the people and in the surroundings you know and love. It offers you time to lay the foundations of a career; for whether you will or no, you can hardly help getting the jobs for which the discharged soldiers will one day look in vain. You do not even have to fear, as Pacifists may have had to fear in the last war, that public opinion will punish you when the peace comes. For we have learned now that though the world is slow to forgive, it is quick to forget.
*I have this seldom-published piece in a little book called The Weight of Glory and Other Addresses.