Age of Empires Series Wiki

Set up a blockade on enemy Home Cities, preventing them from getting any shipments!
—In-game description
Your blockade has arrived.
—Message once Blockade is researched
[Player name] has placed a blockade on the Home City of all your enemies!
—Message when an ally has researched Blockade
[Player name] has placed a blockade on your Home City!
—Message when an enemy has researched Blockade

Blockade is a technology in Age of Empires III that can be researched at the Capitol or State Capitol by European and Federal American civilizations or the Town Center once the Imperial Age is reached by Native American, Asian, and African civilizations. Once researched, it prevents all enemy players from receiving Home City shipments for the rest of the game.

As with Spies, Blockade has a variable cost that depends on how many units that non-defeated enemies have, but with no minimum or maximum limit.

Blockade is unavailable in Treaty – No Blockade. Except if the starting age is set to Imperial/Post-Imperial Age, it is also unavailable in Deathmatch as players cannot advance into the Imperial Age.

Capitol technologies
Blockade · Spies · Knighthood · Peerage · Legendary Native Warriors · Immigrants · Large Scale Agriculture · Deforestation · Excessive Taxation · Cadets · Brigadier General
State Capitol technologies
Age III tech tree aoe3
Oregon Trail · State Constitutions · Statehood
Age IV tech tree aoe 3
Cadets · New Mexico Immigration
Imperial Age
Blockade · Spies · Brigadier General · Legendary Native Warriors · Iowa Farmlands · Pine Tree State · Mountain State Gold Rush
Other civilization's counterparts
AfricanLarge Scale Farming · Ebony Exports · Strangers' Quarters
AsianMechanized Rice Cultivation · Tropical Timber Trade · Collective Economy · Exalted Natives
Native AmericanLarge Scale Gathering · Deforestation · Excessive Tribute · Legendary Native Warriors