Pacifists happen to join armies less.
But also, Nazi leadership was on the shit end of the stick when it comes to WWI. That did not prevented them to start WWII. Instead, the experience normalized the violence for them and shaped their believes. On the other side, Stalin was fighter in particularly cruel war too in his formative years. Was not peaceful either.
Lastly and less importantly, people who had done dying don't vote, they are dead. Only people who survived previous war vote. And survivors often internalized values that are help to survive the war. They sometimes have hard time to adjust to peaceful life afterwards. Your presumption that "only absolutely necessary wars would ever be fought" has no basis in reality.
Also, your theory assumes that enlisted soldiers actions are motivated primary by self-preservation and will vote on that. Some are, but many are not. Others are motivated by duty, career progression, pride, social status, honor, professionalism, tradition, salary, wish to prove themselves or simply by liking to be in the army structure. In case of your hypothetical army, many men will join for career in politics and social status reasons. People motivated primary by self preservation wont join your hypothetical army.
And since the only people who would be voting would be the ones who were or had done the dying, it's likely a very strong anti-war book, as one would presume only absolutely necessary wars would ever be fought.