Blockades

In short#

A blockade is hulls in the water stopping trade that both parties still want. It is not an embargo, which is a political trade ban. You establish one by stationing naval formations on the sea approaches of a country you are at war with and holding them on the Blockade or Sea Denial posture. Pressure builds over several turns, raises the target's trade costs continuously, and only closes trade outright under overwhelming force. It ends when the ships leave, are worn down or are driven off.

What you need#

• A war. Only formations belonging to a country the target is at war with count. A neutral fleet parked on someone's coast closes nothing.
• The right water. A country's trade passes through its home region (if it touches water) plus every navigable region next to it. Those are its approaches. Your ships must be stationed in one of them.
• The right posture. Only Blockade and Sea Denial apply real pressure. Sea Control adds about half a hull's weight, Escort a sliver, Transit and Port nothing. A carrier flying an air mission applies none.
• Sound, supplied hulls. Pressure falls with damage, and much faster below 50 percent condition. Formations far from home, on a hostile coast, or crowded past the port's berths run low on supply and blockade at reduced weight.

How closure is measured#

Each turn the game works out a closure figure from 0 to 1 for every country with a hostile navy nearby:

1. For each approach, sum the lane pressure of hostile formations stationed there.
2. Set that against the approach's port defence, which scales with the port rating of the region. Big developed harbours are much harder to close than an anchorage.
3. Closure on that approach rises with pressure over pressure plus defence. It snaps to total closure only when pressure reaches nine times the port defence.
4. The country's closure is the worst single approach, not the sum. Closing one of three routes into a country does not close the country; a blockade bites when it shuts the way in that matters.

What it does to the target#

Blockade closure feeds the trade engine directly:

• Every trade flow into or out of the blockaded country has its trade affinity multiplied by one minus closure, floored at 10 percent. A partial blockade makes goods cost more to move and shifts buyers and sellers elsewhere.
• At total closure the multiplier is zero and the flow is treated exactly as an embargoed lane: the country's seaborne supply becomes unreachable.
• A blockade on either end of a flow counts. Goods have to leave one coast and arrive at another, and shutting either does it. The heavier closure of the two applies.

Blockade closure is recomputed from current fleet positions during the commodity price step each turn, so a fleet that arrives this turn bites this turn.

Separately, a carrier on station in water touching an enemy land front, combined with your sea control there, cuts that front's supply. That interdiction is capped and escorts and submarines cannot do it on their own; see Naval Vessel Classes.

What it costs you#

The Blockade posture is the most expensive to hold in readiness and has the highest signature, so a blockading fleet is the easiest thing at sea to find and strike from the air. Any hostile fleet entering the region on an aggressive posture forces a surface action whether you wanted one or not, and losses show up in war approval once fleet condition falls below 70.

How a blockade ends#

There is no blockade object to cancel. It exists only while the pressure does, so it ends when:

• the blockading formations change posture, move station or return to port;
• the war ends, since only hostile hulls count;
• the fleet is worn below the point where its pressure matters, through combat or damage;
• the defender breaks it, by driving the fleet off in a surface action, striking it from the air, or bringing enough friendly weight into the region to contest sea control.

Pressure decays faster than it builds once the ships leave, so a blockade is a commitment rather than a toggle.

Where to find it in game#

Order postures and stations from Naval and air command on the country page, which the defence seat holder reaches from the Commands tab of the defence cabinet office. The effect shows up in trade flows and commodity prices for the blockaded country.

Related pages#

• Naval Vessel Classes: hulls, postures, sea control
• Embargo & Trade Exposure: the political route to the same effect
• Trade System: how affinity shapes flows