Surrounded means you know generally where they are. You surrounded them therefore blanket that zone in artillery or gun fire. You are fish in a barrel.
Surrounded means they cannot retreat, get supplies, and potentially receive communications. Morale drops as you run out of food or ammo or toilet paper. No rest or relaxation either.
Wounded are in the center but no hope of getting to an actual hospital.
And who knows how badly you are losing, if help is coming etc.
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