The average citizen would see the odd newsreel about distant wars but it would have no impact on his life. Every day life would go on as normal. Figure now, wars going on in Afghan and Iraq; we see the news and the fighting and watch it for a while before turning over to watch the sport. We rarely see the soldiers (Guardsmen) going off to fight or see them returning. You might see a recruiting office here and there...
The odds on you actually seeing a Space Marine are virtually non-existant and will be the source of legends.
So would there be constant war? No,unless you live on the borders.. and then you are in for a whole world of pain and discomfort!
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