The Guard station is an enemy fortification with a Medium attack radius. The defense is very common in the maps during many battles.
You meet the Guard station first during the battle of Eastshire (battle with Governor James Fierce)
Secondly you see the Guard station during the battle of Western Plains (battle with Chief McDuff)
And the guard station is also in the battle of the Capital District (battle with Viceroy Ville)
It has 5 Health 1 attack damage and 2 Range.