Image:BackArrowGreen.png See the list of buildings In Colonization, the Stockade functions like a city wall. It increases defense of the units inside the colony by 100%. A colony must have a population of 3 or more to build a Stockade. It costs 64 Hammers. A Stockade may be upgraded to a Fort, and a Fort may be upgraded to a Fortress. A stockade is a low wooden barricade made of poles, sharpened at the top, with loop holes for firing muskets, and crude inside shelves for gunners.