+50% settlement defense.
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A Stockade also reduces the chance of a settlement being raided by natives.
Stockades, large stretches of wooden or stone walls built to protect a settlement, were an early necessity for many burgeoning colonies. Effective stockades could be made of a variety of materials. In North America, where strong timber was common, stockades were made almost exclusively by sheering the branches from tall trees and planting the remaining logs side by side around a settlement. In the Caribbean, where the wood was of a lesser quality, earthen stockades could be built into the sides of hills to guard against enemy attacks.