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Europa Universalis IV: How Blockades Prevent Troop Movement

Quick explaination of why the enermy crosses straits when you dont think they should. Or how to trap the Enermy on an island.


Many people ask why the enermy was able to cross a strait they had ships in, usually this leading to losing a war badly and never understanding why. So in an Effort to help ive put together this guide.The Aim of this is to help understand how to lock the enermy behind a strait or help you cross to siege those final provinces.

There are a few exceptions to this guide due to conflicting Movement rules with return province and Zoc (usually seen with Ottomans crossing Constantinople when its controlled by Byzan) I wont be covering Return province rule in this guide – maybe another time.


Blocking movement over traits requires a navy to be present in the straits Sea tile and Control of the neighbouring provinces.

A Country controls a province if

  • Province is on your side of the war and Unseiged – Owned/Allied
  • Province is Enermy side of the war and Seiged by Player/Ally
  • A province Seiged by an Enermy in another war is counted as Neutral.

When done right this will
Prevent troops moving across the strait allowing you to free reign to seige while they have to walk around or even fully lock the enermy onto an island where they will take attrition but be unable to fight in the war.

Block Retreat allowing for a easy stack wipe. Defensivly you could use this to keep the enermy away from your lands unless he has transports allowing you kill them as they land.

Table of Passage

Prov A Sea Tile Prov B Access
You You You You
You You Enermy You
You Enermy Enermy Enermy
Enermy Enermy Enermy Enermy
Enermy Enermy You Enermy
Enermy You You You
You None You Both
You None Enermy Both
Enermy None Enermy Both
Enermy None You Both
You You Neutral You
Neutral You Enermy You
You Enermy Neutral Enermy
Neutral Enermy Enermy Enermy
Neutral none Neutral Both

Extra Info

Neutral is any nation giving access to the war to eirther side.

It doesnt matter what side of the blockade the troops are on troops deseiging one side will be stuck there until they have deseiged even if they own the opposite side. This may give you time to seige the other side maintaining teh trap

It is possible to lock enermy troops in Neutral province if you control the other side access cant be revolked while there are troops in their land so they cant become Blackflagged – Unless Acess is granted through a third party war.

A sea tile is controlled if you have at least 1 ship there that isnt in combat.

Be careful when peacing out War enermys if your trap is on one of their provinces again due to losses of access rights.

How to Trap

So how does all the above help me win my wars.

Trapping the Art of winning the war without a fight – well much of one.

The Ai likes to chase small stacks tehy know they can kill as long as they can reach them though ZOC so we will use this to our Advantage.

A navy bigger than the enermys or enough for local superiority.
small stack of Expendable troops
Decent positioning

Moving a small stack 2-5k to an island and have at least 1 ship or enough to beat Local enermy fleets docked up there.or nearby.

The enermy will send a stack after this army if they can reach it and start a battle.
Undock your ships and retreat from battle blocking the whole enermy stack. They will seige your island but will be unable to leave. You can leave them here for the Duration of the war or stack wipe them when you have a decent army spare.If 2 stacks are coming for the battle wait for all to enter battle before moving the ships.

If your trying to trap in hostile or neutral land while battle is being fought seige down the mainland side with your other army the strait crossing time should give you time to do this.

Written by Omniconda

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