A blockade is a naval action intended to keep goods from entering and/or leaving a port.
A blockade will happen automatically any time the following conditions hold:
- One or more countries have a large enough naval force in a sea zone which a port opens into.
- The naval force is not moving, and not engaged in combat.
- The port settlement is controlled by an enemy country of the blockading fleet(s).
For this purpose, the naval force in a sea zone is all of the non-moving fleets, of all enemies of the country controlling the port. A naval force is large enough to blockade if it is 5 warships, or 10 galleys, or any combination of warships and galleys such that:
2*#warships + #galleys >= 10
On the map, you can tell when a port is blockaded because its symbol will change to a "blockaded port" symbol.
Effects of Blockades
Here is a list of the effects of a blockade:
- A blockade helps to advance the siege, if there is one, in the blockaded city. Against higher fortifications levels, a blockade can be required to get any siege advancement.
- A blockade doubles supply in the blockaded province.
- Each blockade of a country's ports will reduce the trading income it gets from overseas CoTs, proportionate to the number of blockaded ports (this needs to be confirmed).