Naval warfare

This page deals with naval combat mechanics. For information on the recruitment and maintenance of navies see navy. For details about ship types see naval units. For the state of war see warfare.

Naval warfare is the competition of sea-going power between nations at war. While a majority of warfare is land-based, the naval aspect of conflict can be incredibly influential in the spheres of trade, colonisation and conquest.

Sea battle interface

The naval combat interface

Like land warfare, naval combat occurs when opposing fleets confront each other in the same sea province. Also like land battles, these sea battles can go on for many days, so they should be considered not as a single engagement, but as two fleets maneuvering to gain wind, standing off and skirmishing before the fleets finally collide.

In EU4, there is no player involvement inside combat, but the interface now displays more information, showing among other information which ship is fighting which. The naval combat interface shows the strength of the two fleets engaged in the combat. Combat will begin with a contest of firepower, followed by shock action in which ships attempt to grapple or ram one another. This sequence will alternate until one of the fleets loses morale and is either routed or destroyed. The condition of each ship is expressed as a percentage, and hovering over a ship with the mouse cursor will produce a tooltip which identifies which opposing ship they are currently firing on, as well as their current morale, their strength, and the ship type.

Engagement width

Since the patch 1.16, combat width for naval warfare has been introduced, it has a base of 25, and can be modified by:

• admiral's maneuver +10% per pip
• Coastal sea +10%

	Traditions	Ideas	Bonuses	Policies
+20%	—	Piratical idea 4: Sail in Consort	—	Naval-Exploration: Skilled Cartographers
+10%	—	Naval idea 7: Superior Seamanship	Danish ambition	Naval-Espionage: The Maritime Intelligencer Unit

Heavy ships occupy 3 combat width, while galleys, transports and light ships each occupy 1 combat width.

Unlike the 'combat width' of land warfare, the 'engagement width' of the two participants are independent, that means one participant could have wider engagement width than the other.

Combat sequence

The conclusion to a naval engagement

Like land warfare, naval combat occurs when opposing fleets confront each other in the same sea province. Also like land battles, these sea battles can go on for many days, so they should be considered not as a single engagement, but as two fleets maneuvering to gain wind, standing off and skirmishing . A sea battle will last until one side is routed or annihilated. Patch 1.16 also introduced the concept of a naval combat width, and much like its land cousin it is the total number of ships that can engage the enemy at any one time.

Engagement

While there is an ongoing naval battle, fleet's ship will try to populate its engagement width until the limit is reached, in the following order:

1. Heavy ships
2. Galleys
3. Light ships
4. Transports

Any ships already disengaged will be ignored.

Phases

Combat is divided into a series of 3-day phases. Phases alternate between fire and shock, with the fire phase happening first.

Target selection

In combat each ship will try to find a target and make an attack. Every enemy ship has a base chance of 10 to be picked as a target, further modified by:

• +0 to +5 random chance
• +5 if same type
• x0.1 if morale at 0 or less
• x2 if damage less than 50%

Enemy ship with best score is picked as a target. If the previous target is about to die, a new one will be picked.

Die roll

At the beginning of each phase, each side rolls a die. The result is used to determine the morale damage and hull damage inflicted by that side during each of the three days of that phase.

Hull damage

Base damage is calculated according to the following formula:

Base Hull Damage = 0.025 + 0.025 * (2 + Dice + Combat Modifiers)

The amount of cannons of the attacking vessel affects the hull damage dealt and the hullsize of the defender decides how long it can stand the cannon fire.

The Artillery Fire Modifier gives a bonus or penalty to damage dealt depending on if attacker or defender has a technological advantage.

• Attacking unit modifier: The attack modifier from the attacking unit's technology, i.e. "Artillery Fire".

Artillery Fire Modifier = Attacker Artillery Fire - Target Artillery Fire

• Attacking unit Combat Ability: Any Combat Ability bonuses the attacking unit has.

Final Damage = 0.03 x Base Hull Damage x Ship Strength x (Cannons / Target Hull) x (1 + 0.05 x Artillery Fire Modifier) x (1 + Ship Combat Ability + Combat Ability from Admiral) / (1 + Target Ship Durability)

If target ship Morale is 0 or below, Final Damage is multiplied by 10.

Galleys fighting in the inland sea have their Final Damage doubled.

Morale damage

Morale is damaged both over time during a battle and also when a friendly ship is sunk.

Base Morale Damage = 0.25 x (Country Naval Morale / 3) x Base Hull Damage x Ship Strength x (Cannons / Target Hull) x (1 + 0.05 x Artillery Fire Modifier) x (1 + Ship Combat Ability + Combat Ability from Admiral)

Several ideas decrease the amount of morale lost when a ship is sunk:

	Traditions	Ideas	Bonuses	Policies
−33%	Naval idea 3: Naval Cadets	Portuguese idea 1: Legacy of the Navigator	—	Humanist-Maritime: The Citrus Statute
−20%	Betsimisaraka traditions	Galician idea 6: Sailors of the Cantabrian Sea Naxian idea 2: Naxos Rules The Waves	Catalan ambition	—
−10%	—	—	—	Naval-Religious: Zealous Captains

	Conditions
+10%	Admiral with Level-headed personality

Disengagement

Any ship with less than 0.5 morale will try to disengage from the battle. Whether it will be successful depends on the ship's Disengagement Chance. The base value of this chance is 3% but can be modified by some national ideas.

	Traditions	Ideas	Bonuses	Policies
+5%	—	Australian idea 5: Royal Australian Navy Danish idea 3: Old Naval Traditions Portuguese idea 1: Legacy of the Navigator	—	—

Combat statistics

Cumulative diplomacy technology effects to navy

Dip Tech Level	0	3	7	8	12	18	22	25	27	29	31
Morale of Navies	+2.0	+2.1	+2.4	+2.6	+3.0	+3.5	+4.0	+4.5	+5.0	+5.5	+6.0

Cumulative military technology effects to navy

Mil Tech Level	0	7	13	16	22	25	32
Artillery Fire	+0.0	+1.0	+1.4	+2.4	+4.4	+6.4	+8.4

Max naval morale

The following contributes to the maximum morale of a nation's navy.

Factor		Amount
	Naval maintenance	20% at minimum maintenance (minimum of 0)
		100% at maximum maintenance (multiplicative modifier)
	Navy tradition	+25% at 100 navy tradition
	Prestige	+10% at 100 Prestige, −10% at −100 prestige
	Power projection	+10% at 100 power projection
	Naval reformer advisor	+10%
	Defender of the Faith	+5%
	Bankruptcy	−50%
	War exhaustion	−2% per 1 war exhaustion

Certain National Ideas, Idea groups and policies will bump naval morale.

	Traditions	Ideas	Bonuses	Policies
+20%	Alaskan traditions British traditions	Genoese idea 2: The Lessons of Chioggia Kono idea 3: Oyamazumi Shrine Norwegian idea 1: Natural Seamanship So idea 3: Fight for Tsushima	Luzon ambition	Quality-Maritime: The Organized Marines Act
+15%	Omani traditions	Bregenzer idea 7: The Lake Constance Navy Chiba idea 7: Naval Reform Corsican idea 2: The Battle of Meloria Madyas idea 2: Legacy of Panai Manx idea 4: Mann and the Isles Ouchi idea 3: Protect Against Piracy Sicilian idea 6: The Grand Navy	Dalmatian ambition Mogadishan ambition Ragusan ambition Siddi ambition	—
+10%	Candarid traditions	Naval idea 7: Superior Seamanship Quality idea 5: Naval Drill Danish idea 3: Old Naval Traditions Piratical idea 5: Elected Quartermasters	—	Exploration-Defensive: The Naval Secrecy Act Religious-Maritime: Chaplains of the Fleet

Each point of naval tradition also increases naval morale recovery by +0.10%.

Combat ability

Combat ability is a value that is multiplied with the units' damage dealt (both for casualties and morale), but only for the specified type of unit.

Heavy ship combat ability improvement

	Traditions	Ideas	Bonuses	Policies
+20%	—	Naval idea 6: Oak Forests for Ships	—	—
+15%	British traditions	—	—	—
+10%	—	Butuan idea 6: Protect the Coastlines Date idea 5: Red Seal Ships English idea 1: A Royal Navy Spanish idea 4: A Spanish Armada	Alaskan ambition Genevan ambition	Innovative-Maritime: New Naval Tactics

Light ship combat ability improvement

	Traditions	Ideas	Bonuses	Policies
+25%	—	—	Veronese ambition	—
+15%	Alaskan traditions Cham traditions Ferraran traditions	Icelandic idea 4: Armed Merchants Moluccan idea 6: Alliance with the Papuans	Arakanese ambition Holstein ambition	Maritime-Plutocratic: The Protected Shipping Lanes Act
+10%	Hamburger traditions Pattani traditions	Somali idea 6: Corsairs of the Red Sea Sumatran idea 3: Spice Pirates	—	—

Galley combat ability improvement

	Traditions	Ideas	Bonuses	Policies
+25%	—	Naval idea 2: Improved Rams	Venetian ambition	—
+20%	Aragonese traditions Barbary Corsair traditions Cebu traditions Hosokawa traditions Ionian traditions Tunisian traditions	Berber idea 7: The Brothers Barbarossa Cypriot idea 6: Repel the Corsairs Italian (cU) idea 3: Mare Nostrum Kitabatake idea 4: Kuki Suigin Knights Hospitaller idea 4: Reconquista of the Sea Moroccan idea 4: Defend the Coastline	—	—
+15%	—	Kono idea 5: Rule Over the Inland Sea	—	Maritime-Quantity: Streamlined Galley Production
+10%	—	Naxian idea 1: Maritime State So idea 2: Wakou Tradition	—	—

Transport combat ability improvement

The combat ability of transports is not modified by the base game.

Unit pips

Main article: Naval units

Each ship has stats in three categories: Hull, Cannon, and Speed.

Hull is the defensive stat, and cannons the offensive stat. With the exception of Morale, every combat phase the hull/cannon pips are used against each other to calculate the number of hull damage of each combat phase.

Leader pips

Leaders are rated on a scale of 0 to 6 for each of the following skills:

• Fire, Shock

The leader's skill is added to the dice roll of its respective phases.

	Traditions	Ideas	Bonuses	Policies
+2	—	Dutch idea 4: Instructie voor de Admiraliteiten	—	—
+1	—	Naval idea 3: Naval Cadets Ferraran idea 7: The Ferraran Arsenal Norman idea 7: Great Commanders Tunisian idea 5: Board of Captains	Corsican ambition Madyas ambition	Naval-Innovative: The Nautical Education Act

	Traditions	Ideas	Bonuses	Policies
+1	—	Naval idea 1: Boarding Parties Madyas idea 4: Masters of Maritime Warfare	—	Naval-Religious: Zealous Captains

• Maneuver

The leader's maneuver affects the movement speed of the fleet both on the map and in battle. Each point also grants 5% additional trade power when assigned to a fleet protecting trade in a trade node. Finally, it reduces attrition taken by 1% per skill level.

	Traditions	Ideas	Bonuses	Policies
+1	Madyas traditions	British idea 7: Britannia Rules the Waves Mahri idea 4: Pilots of the Arabian Sea Mogadishan idea 2: Somali sailors Omani idea 6: Skilled Captains Spanish idea 4: A Spanish Armada Swahili idea 2: Monsoon Season	—	Innovative-Maritime: New Naval Tactics Maritime-Offensive: Hold the Weather Gauge

The conclusion to a naval engagement

Concluding a battle

A naval battle ends when one side is either:

• Reduced to 0 morale; or
• Flees from combat; or
• Annihilated

Upon victory, ships from the defeated fleet may be captured, depending on the difference between the two fleets' maneuver skill. Generally very little to no ships will be captured for leaderless (0 vs. 0 maneuver) battles.

If the defeated fleet still has ships remaining, it will escape to the nearest friendly port to repair and recover its morale. Naval battles, like land battles, may cause war exhaustion as well as affect warscore, naval tradition and prestige. Note that warscore gained from naval battles will generally be insignificant compared to those gained by its land counterparts.

Several ideas increase the chance of capturing ships after a battle:

	Traditions	Ideas	Bonuses	Policies
+33%	—	—	—	Naval-Diplomatic: Terms of Surrender Statute
+20%	—	Betsimisaraka idea 5: European Pirate Communities	—	—
+15%	—	Knights Hospitaller idea 4: Reconquista of the Sea	—	—
+10%	—	Cornish idea 4: Pirates of Penzance Dithmarscher idea 4: Expert Wreckers Kono idea 7: Murakumi Suigun Pattani idea 4: Lian Dao-Qian Band	—	—

Morale and strength

Morale

"Morale of navies" redirects here. For bonuses that increase naval morale, see § Max naval morale above.

Morale is an important factor in fighting battles. Each turn of combat a unit will take a Morale hit. Once a fleet's average Morale value has been reduced to zero the fleet will attempt to retreat. Retreat cannot happen until both a fire and a shock phase have completed, so a fleet that has its morale reduced to 0 before that point will be destroyed.

If a fleet loses a battle while having low enough morale, they will be forced to retreat to a port of the nearest sea province. While retreating, it cannot be engaged in combat or be controlled until it reaches the sea province, nor will it repair. The fleet will also move 50% faster, and will recover morale at a normal rate during the retreat.

After every battle is fought a fleet must spend some time not fighting for its morale to recover.

Morale recovery

Every month when docked at a home port, a ship recovers a 10% of its maximum morale.

Certain National Ideas, Idea groups and policies will increase naval morale recovery.

	Traditions	Ideas	Bonuses	Policies
+5%	—	—	—	Humanist-Naval: The Naval Inspection Act Naval-Innovative: The Nautical Education Act Religious-Maritime: Chaplains of the Fleet

Each point of naval tradition also increases naval morale recovery by +0.1%.

Unit strength

Unit strength is an important factor in fighting sea battles. Naval unit strength affects how long it can stand cannon fire before sinking. Each turn of combat a unit will take hull damage reducing its strength.

Galleys gain a bonus 100% strength in inland seas which are shown on the map below in pale blue.

Terrain map.

Ship repair

Fleets that have sustained damage will automatically repair up to their full strength when docked in an owned, allied, or in a province with fleet basing rights. There is a 'repair damaged' button that will detach damaged ships and send them to a nearby port to repair, when they are back up to full strength they will rejoin the fleet.

Main article: Navy#Ship_Repair

Naval doctrine

A country that has a naval force limit of at least 20 may select a naval doctrine. Selecting a naval doctrine, or changing to a different one (which can be done at any time), costs 0.1 ducat per sailor cost of the country's navy (i.e. 5 per light ship or transport, 10 per galley, and 20 per heavy ship).

The doctrines are:

Doctrine	Effect	Notes
Fleet In Being Our naval influence shall be felt without the expense of our fleet leaving port except under the most favourable of conditions.	−15% Naval maintenance modifier
Free Oarsmen We shall fight the temptation to have slaves and the condemned rowing our Galleys. Free men, resilient in the face of adversity and resistant to defection shall form the muscle of our navy.	+15% Galley combat ability
Merchant Navy Our fleet's prime directive is to serve the financial interests of the State. Every effort shall be made to ensure our cargo ships are laden with foreign riches.	+33% Ship trade power
Ship Boarding With established Prize Law and generous Letters of Marque we will nurture a custom of seizing enemy ships intact.	+33% Chance to capture enemy ships
Wooden Wall In a world of rapid change the seas remain of crucial importance to our nation. Both as means to secure our dominance and as the first line of defense our wooden wall shall prevail.	+1 Naval combat bonus off owned coasts	Requires British culture group
Grand Armada A grand convoy shall accompany the treasure fleets that bring the wealth of the Americas into our home ports.	+50% Treasure fleet income	Requires Iberian culture group, but not Portuguese or Brazilian
Portuguese Marines To establish a truly global empire we must be skilled at launching assaults on enemy forts from the sea.	+1 Blockade impact on siege −40% Naval barrage cost	Requires Portuguese or Brazilian culture

Fleet actions

Start patrolling

The start patrolling button orders a fleet to loop its current movement order: when it reaches the final destination of its current set of movement orders, it will automatically head back to the point where the patrol was started. Patrol routes can include port visits, where the patrol stops until all ships are repaired. While the same function can be fulfilled by light ships assigned to protecting trade nearby, patrols are not limited by ship type, trade power, or trade range.

Coastal Raiding

Costal Raiding is a naval ability added in the Mare Nostrum expansion which allows fleets belonging to nations with the Raid Coasts idea, which in the base game belongs to the Maghrebi culture group ( Morocco, Tlemcen, Tunis and the formable nations of Algiers and Tripoli), Habsan and The Knights to raid the coasts of other nations of a different religion for loot (ducats) and sailors. This idea is also available to Custom Nations.

The Golden Century DLC introduces Pirate Republics (specifically; New Providence, Tortuga, Port Royal, So, Palembang (through an event) and Custom Nations with the Pirate Republic government), which also have the ability to raid coasts and are capable of raiding the coasts of countries with the same religion.

Historically, this ability reflects the raids carried out by Barbary pirates which were active in the Mediterranean Sea during the mid-16th to early 19th centuries while in the case of the three Pirate Republics, it simulates the Golden Age of Piracy in the Caribbean Sea from the mid-16th to the early 18th century. So is a special case, as it represents a resurgence of the Japanese Wokou Pirates that raided the coasts of East Asia intermittently from the 4th century to the 17th century.

Raiding can provide a significant early-game boost to the income and sailor pools of nations that can do it and can also serve as a way to damage the economy of other nations. An example of this is So, which can employ Coastal Raiding against Ming to pile up devastation and cause Ming to potentially lose the Mandate of Heaven and collapse.

Requirements

Raiding coasts as Morocco.

Raiding a coast is something fleets can do at sea. To raid a coastal province, the following needs to be true:

• the nation…

• …has either…
  • …the May raid coasts idea (i.e. countries with Berber national ideas or The Knights)
  • …the "Pirate Republic" government form/reform
• …must be able to place a fleet in a sea tile adjacent to the province, but doesn't need to be able to blockade the port

• the target province…

• …must be no more than three sea tiles away from a province owned by the nation (cored or otherwise)
• …must have a development lower than or equal to the blockading power of the fleet
• …does not have the religion of the raiding nation, unless the raiding nation is a Pirate Republic
• …does not belong to an ally or subject of the raiding nation
• …does not have the “Raided Coast” modifier

After a province has been raided, its loot bar is emptied, the amount of devastation is increased, and the modifier “Raided Coast” is applied for ten years. Each raided province will add a −25 relations penalty with the target country (up to a maximum of −100), decaying by +1 per year.

The efficiency of raiding is reduced by fleets on pirate hunting patrol.

When a coast is raided, the loot provided is as follows:

Raided coast	Conditions
+1	per development (raided province)
+ sailors	Local sailors per Raided provinces / 4

Blockading

Fleets will automatically blockade a coastal sea province under hostile control while they are stationary and have no other orders.

Blockade power

The blockade power (sail speed in the tooltip) of a fleet is displayed after the blockade icon in the fleet panel. It is mainly determined by the tactical movement speed of the fleet's ships.

${\text{blockade power}}={\frac {\sum {\text{speed of ship}}}{3}}\cdot {\text{blockade efficiency}}$

Each point of blockade power will be able to blockade one development point of a province.

Blockades will only take effect if there is enough blockade power to match the full development. If a fleet does not have enough blockade power to blockade all adjacent provinces under hostile control, it will assign its blockade power in precedence of:

• Hostile province under a siege lead by any friendly force
• Hostile province with the lowest development
• Hostile rebel province with the lowest development

The detach blockade button () in the fleet panel will detach a fleet of sufficient size to blockade all enemy ports neighboring the sea province.

Blockade efficiency

Blockade efficiency is determined by:

	Conditions
+1%	for every point of navy tradition

Ideas and policies:

	Traditions	Ideas	Bonuses	Policies
+50%	—	Maritime idea 7: Naval Fighting Instruction	—	Naval-Maritime: The Naval Supremacy Act
+33%	—	British idea 7: Britannia Rules the Waves	Omani ambition	—

Decisions and events:

	Event modifier	Trigger	Duration
+20%	Improved Blockade Tactics	Maritime ideas event: Improved Blockade Tactics	for 10 years.
−25%	Blockade Standards Slipping	Maritime ideas event: Slipping Standards Option: ‘Well we can't expect them to operate at peak efficiency all the time’	for 10 years.

Effects of blockade

A blockade has a number of effects on any neighbouring land provinces occupied by an enemy:

	+20%	Local recruitment time
	+20%	Local shipbuilding time
	+0.1	Monthly devastation

Notably, provinces producing Spices get negative monthly devastation that exactly counteracts the positive modifier from blockades.

Blockading a country's ports also applies the following modifier, scaled by proportion of (core, state) development blockaded:

+0.10

Monthly war exhaustion

Blockades have the following further effects:

• Siege: −2 penalty to die rolls in non-blockaded coastal provinces, except those owned by primitives. (Provinces without ports, e.g. on the Caspian Sea, don't count.)
• War score: Blockades are worth war score scaling with the proportion of development they represent and local autonomy. Capital and fortified provinces are worth more. Some casus belli have blockades as a war goal.
• Spoils of War: Blockades add ducats to the blockader's treasury (listed under "Spoils of War") in proportion to the province's income.
• Restriction of movement: See § Blocking a strait below.

Blocking a strait

To block a strait the following requirements must be met:

• The blockading alliance or a neutral nation have to control (owns or occupied) at least one side of the adjacent provinces
• The blockading alliance have to control the sea by a naval force (blockade efficiency doesn't matter)

As a consequence, if a war alliance controls both sides of the strait they can march over regardless of blockades.

Examples:

• A war participant controlling both sides of a strait: The Ottomans can cross the strait at Bosphorus as long as they have control of Constantinople and Kocaeli even when the enemy controls the sea. Same system applies for the second strait between Edirne and Biga.
• A neutral nation controlling a side of a strait: Ulster, controlling Ulaidh, cannot cross the strait across the Irish Sea to Ayrshire in Scotland if Ulster is only at war with England (Scotland is neutral and gives military access to one of the war participants), and England controls the Irish Sea.
• However, if Ulster has called in an ally, say Burgundy, and Burgundy is in a separate war with Scotland and controls Ayrshire, then the first requirement is no longer fulfilled, and the Irish nation can cross the strait despite England having control of the Irish Sea.

Besieging a province of a strait does not fulfil the first requirement; the siege must finish, translating to control.

Naval missions

Fleet missions are grouped together under a collective “Select Mission” button () that allows the player to tell their fleets to;

• Protect Trade
• Privateer
• Hunt Pirates
• Explore
• Hunt Enemy Fleets
• Blockade Enemy Ports
• Intercept enemy fleets

Protect trade

This mission is available to any fleet that contains light ships. It will add the trade power of the light ships in the fleet to any maritime trade node that the player already have some trade power in, provided that the trade node is within both trade range and supply range.

The trade power of light ships depends on ship model, and increases as diplomatic technology advances. Furthermore, it scales linearly with the naval maintenance slider, reaching full potential at maximum naval maintenance, but suffering a −75% penalty at minimum naval maintenance. AI nations do not suffer a trade power penalty to light ships from low naval maintenance.

Privateer

This mission is available to any fleet that contains light ships. The fleet will hoist the Jolly Roger and add the trade power of its light ships to a pirate nation in any selected trade node. Unlike the protect trade mission, existing trade power is not needed in a trade node to start a privateer mission.

Privateer efficiency

Light ships on privateer missions receive a +50% bonus to their trade power. Privateers do not inherit any national bonuses or penalties to global trade power. Factors such as overextension or halved trade power when collecting in foreign nodes are notably ignored. The trade power of privateers is instead affected by various privateer efficiency modifiers:

	Traditions	Ideas	Bonuses	Policies
+50%	—	—	—	Naval-Maritime: The Naval Supremacy Act Offensive-Exploration: Letters of Marque
+33%	—	Espionage idea 6: Privateers	—	—
+25%	—	Maritime idea 7: Naval Fighting Instruction Cebu idea 5: 'The Place for Trading' Mindanao idea 7: Pirates of Mindanao Naxian idea 3: Archipelago Of Opportunities	—	—
+20%	Barbary Corsair traditions	Cornish idea 4: Pirates of Penzance Dithmarscher idea 4: Expert Wreckers Kono idea 7: Murakumi Suigun So idea 4: Bahan Ship	—	—
+15%	East Frisian traditions Gutnish traditions	Al-Haasa idea 7: Legacy of Ramah ibn Jabir Arakanese idea 4: Magh and Ferenghi Betsimisaraka idea 2: Pirate Ports Cypriot idea 7: Raid Turkish Commerce Malagasy idea 3: Pirate Ports Montenegrin idea 4: Balkan Gusars Moroccan idea 5: Protect Pirate Republics Munster idea 6: Pirate Haven Norman idea 5: Viking Raids Novgorod idea 6: Funding the Ushkuiniks Pattani idea 4: Lian Dao-Qian Band Pomeranian idea 1: Legacy of Pirates Sumatran idea 3: Spice Pirates	—	—
+10%	—	Berber idea 4: Corsairs Sonoran idea 5: Taking What's Ours Tunisian idea 3: Corsairs	—	—

The trade power of ships assigned to the privateer mission affect the trade power they have in the node, this means that the flagship +1 trade power per ship modification and the +33% ship trade power merchant navy naval doctrine, as well as other ship trade power modifiers affect privateers.

The Enlist Privateers decision increases privateer efficiency by another +25%. It becomes available at 8 Diplomatic technology and requires the nation to have completed Maritime ideas, a ruler with 3 Military, as well as 50% of the force limit.

With Common Sense, winning a parliament debate "Issue Letters of Marque" provides +15% privater efficiency for 10 years.

Each point of naval tradition also increases privateer efficiency by 0.25%. The total trade power from privateers is thus

privateer trade power = trade power from light ships × 1.5 × (1 + naval maintenance modifier) × (1 + privateer efficiency)

Note that without Wealth of Nations, El Dorado, Mare Nostrum or Golden Century DLC enabled the modifiers are exchanged. Privateer efficiency is replaced by trade power abroad.

Range

Privateer fleets can only reach trade nodes in sea zones that are within trade range. A nation's trade range extends from cored provinces of the nation or its subjects, as well as coastal ports of any nation that has granted it fleet basing rights.

Trade range can be increased by diplomatic technology, decisions, ideas, and policies:

	Traditions	Ideas	Bonuses	Policies
+33%	—	Ryukyuan idea 4: Maritime Commercialism	—	—
+25%	Swahili traditions	Trade idea 3: Merchant Adventures	—	—
+20%	—	Ayutthayan idea 5: Promotion of Trading links Gujarati Princedom idea 7: Extend Trade Routes to Africa Gujarat Sultanate idea 2: Jain Connections Kono idea 6: Trade With Continental Asia Malabari idea 1: Merchants of Southern India Mesoamerican idea 7: Obsidian and Jade Mogadishan idea 1: Indian Ocean Trade Pacific Northwest idea 2: Dugout Canoes South Indian idea 1: Merchants of Southern India	—	—
+15%	Traditions of The Hansa Sumatran traditions	Evenk idea 2: Reindeer Herding	—	—
+10%	—	Dutch idea 2: Dutch Trading Spirit Mamluk idea 1: Red Sea Trade West Indies idea 4: The American Trade Hub	—	—

Effects

The privateer fleet increases the trade power of a pirate nation that acts as a collector in the trade node. This pirate nation will submit 40% of its earnings to the nations that commissioned the privateers contributing to its trade power. The presence of this pirate nation effectively reduces the share of trade value controlled by all non-pirate nations in the node. Income from privateering will be recorded in the economy window as spoils of war.

Any country that would have more than 20% of the trade power in the node without privateers will receive a casus belli against any nation that has sent privateers to that node.

Any country that would have more than 10% of the trade power in the node without privateers will have a −1 opinion modifier per month of any nation that has send privateers to that node, capped at −100.

Sending light ships on privateer missions against rivals is one of the easiest ways to acquire power projection. This can be especially useful to increase the power projection of the player beyond +25 for +1 free leader, or beyond +50 for +1 / +1 / +1 each month.

Activating a privateer mission will force the game to update a nation's power projection on the next game day. This will consequently update, among other things, the trade power in trade nodes and the nation's military force limits. Triggering an update like this can be useful when game stats are temporarily desynchronized due to certain actions, such as sending light ships to protect trade or changing local autonomy levels.)

Hunt pirates

This mission is available to fleets which contain at least one ship that isn't a transport. Fleets containing heavy ships or light ships may hunt pirates in any non-inland trade node; however, fleets containing only galleys (as well as fleets which are a mixture of galleys and transports) can only hunt pirates in nodes where all nearby sea provinces are inland seas, e.g. in Basra and Alexandria, but not in Hormuz. This does not necessarily mean that fleets will only hunt in inland sea provinces (where they are more effective): for instance, a fleet hunting pirates in Canton will use the Luzon Strait.

The total number of guns of the ships is used to find the efficiency at which they hunt the pirates. The trade power of pirates is reduced by hunt pirate efficiency. 0%, when no fleet is hunting pirates, up to 99%, if the total number of guns from the hunting fleet is greater than or equal twice the total number of guns from pirating fleet.

In addition, it is helpful to know that this is also effective at stopping other nations from raiding your coasts.

Note that pirate fleets and fleets hunting pirates do not actually battle or otherwise damage each other, unless the countries that own the fleets are at war with one another.

Explore

This mission requires an explorer, and a total of 3 light and/or heavy ships. It sends the fleet to explore a region or a coast line, that can be chosen by either selection the region on the UI or clicking on the naval TI with the "explore" tab opened, and the player can attempt to circumnavigate the globe at diplomatic technology 9.

Main article: Colonization#Discovery

Hunt enemy fleet

The fleet will hunt enemy fleets in a specific sea region, that can be chosen by either selecting the region in the UI or clicking on the naval region with the tab opened.

Blockade enemy ports

The fleet will blockade enemy ports and evade enemy fleets that are not significantly weaker. (Can be altered by setting the fleet to be Bold.)

Main article: Naval warfare#Blockading

Intercept enemy fleets

This mission will have the fleet seek out enemy fleets near allied coastlines, focusing on troop transports.

Strategies and tactics

Deployment

Due to the lack of stacking penalty, optimal strategic deployment in terms of combat results follows decisive battle doctrine strictly - concentrate all ships in one fleet, seek battle if one has superior naval assets, and hide otherwise. Naval admirals can significantly tilt a battle in one's favor, even more so than generals; without an admiral, stack wiping and sometimes even victory becomes unlikely even with seemingly overwhelming advantage.

However, other factors may complicate this. A country may be forced to divide their fleet if they have naval objectives other than destruction or suppression of the enemy navy, such as protecting (multiple) trade nodes, transporting land units by sea, exploring, patrolling for pirates, reconnaissance, blockading and so forth. If the country lacks naval supremacy compared to their enemies, they may be forced to risk losses, support fewer of these objectives at the same time, or leave the sea entirely for the duration of the war.

Bringing an enemy fleet to battle

A country with a naval advantage may wish to bring a reluctant enemy fleet to battle. This can be accomplished in several ways:

• If the enemy fleet is docked at a port, they cannot be attacked directly. However, the fleet may be ejected by occupying (successfully sieging) that province, at which point the leaving fleet will enter into combat with any opposing fleet(s) in the corresponding sea province.
• A small "bait" fleet may be used to lure the enemy into attacking, whereupon the main fleet can reinforce from a nearby sea province or port. This can also be used to lure fleets into or out of inland seas, where galleys have a relative advantage.
• Light ships move faster than heavy ships / transports, which move faster than galleys. A fleet without galleys can easily catch an enemy fleet that contains galleys.
• Putting your ships into port will usually cause the AI navy to be more aggressive and leave port, sometimes even attempting a full blockade, leaving their navy significantly more vulnerable.
• After a defeat, an enemy navy will typically retreat to an adjacent port. Having an army already sieging down this port will give you a significant advantage, as the ships will be forced to leave port with low morale and no repairs, allowing for a stackwipe or a victory in which they lose most of their ships.
• Sometimes a bug will allow the AI remain permanently in a province even if it is sieged down. The only way to fix this is to retreat several sea tiles from the province and then go into port, or in other words give the ai an illusion of safety.

Footnotes

Mechanics

Defense

Fort • Zone of control

External relations=

Customization

Nation designer • Random New World

Ages and Institutions

Ages • Institutions

Innovativeness and Technology

Innovativeness • Technology