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Naval Primer

Template:Anthology Reflecting its historical roots, land warfare is the most important aspect of HoI2: both air combat and naval combat have more limited roles. Naval power is most important for nations that require naval supremacy in order to achieve their land warfare objectives: Japan and the USA.


Naval Strategy

Selecting an appropriate naval strategy from the beginning of the game, and consistently following that strategy throughout the game, is essential. Navies take an extraordinarily large amount of industry and time (IC days) to build and cannot upgrade (except for naval brigades added in [Armageddon]), thus changing directions on a whim is not possible.

Projection or Defence

Force Projection

The USA and Japan are the two major powers that require a Navy in order to project force around the world. Both nations have significant advantages in producing the most advanced and powerful navies in the world. The projection of force means the ability to move land forces at will, and this requires complete naval supremacy.

Home Defence

The UK, Italy, and Germany all require a Navy for the primary role of defending their territories. Although the UK begins with a powerful Navy, both Germany and Italy begin with relatively weak navies. While force projection requires naval supremacy in order to safely transport troops, the key component to home defence is a guerilla warfare style of naval interdiction. Germany has the ability to personify this strategy through the use of submarine warfare. Ultimately, however, guerilla strategy can never be successful in the long term without supporting conventional forces.

Starting Navies

Each strategy guide will go into more depth regarding how to handle starting navies. As a general rule, the player should first reorganize all navies into appropriate fleet groups (see below). Once accomplished, three basic methods are often suggested:

  • Retain navy: Use existing navy for limited roles according to fleet composition (see below).
  • Disband early models: This saves a small amount of supplies. Generally this is only suggested for smaller ships (like DD), and almost never for Battleships and Carriers.
  • Trade early models: Exchange naval vessels with allies in exchange for supplies and resources.

Naval Research

  • Research naval vessels as early as possible due to the long build time required.
  • Quantity is more important than quality: It is far better to have four 1938 Battleships, than two 1941 Battleships.
  • Carriers are a special unit due to the carrier air group: these will upgrade as technology advances. The carrier level is far less important in combat than the level of the CAG.
  • Naval doctrines are very important for effective combat. For more information see Naval Doctrine.
  • Only the United States has the capability to research every naval technology, and even then they won't get them in time to be ready for hostilities.
  • See the Research guide for general research advice.

Ship Strengths & Weaknesses

Capital Ships

Carriers (CV): (aka Kings of the Sea)


  • Excellent combat effectiveness in long-range naval engagements
  • Good visibility and sea detection
  • Carrier Air Groups (CAGs) can be upgraded


  • Poor combat effectiveness in short-range engagements
  • Expensive to build and repair
  • Strong carriers come late in the game (1942)

Light Carriers (CVL): (aka Carrier Killers)


  • Excellent in visibility and detection
  • Imperative ides for surface fleets (less so in the 1.3beta Armageddon patch)
  • Good air defense and submarine defense


  • No real combat capabilities

Battleships (BB): (aka Queens of the Sea)


  • Most powerful surface vessel in close combat
  • Most powerful shore bombardment


  • Poor visibility, sea detection, and sub detection
  • Expensive to build and repair

Battle Cruisers (BC): (aka Scrap Metal)


  • Average combat effectiveness
  • Slightly stronger and tougher than heavy cruisers


  • Poor visibility, sea detection, and sub detection
  • Expensive to build and repair

Heavy cruisers (CA): (aka Poor Man's Battleship)


  • Most cost-effective capital surface vessel for close combat
  • Most cost-effective shore bombardment


  • Decent visibility, sea detection, and sub detection

Submarines (SS): (aka Silent Killers)


  • In ARMA: cost effective combat unit in wolfpack sizes (preferably 30 pack)
  • In HoI2: good combat capabilities
  • Excellent convoy raiding capabilities
  • Cheap to build and research, poor man's navy


  • In DD: extremely poor combat capabilities
  • Late-game ASW is deadly for submarines (1.3beta Armagddon patch only)


Light cruisers (CL)


  • Decent combat effectiveness, toughest screen
  • Good Combat Range, can support Heavy Cruisers in combat


  • Relatively expensive to build and repair for a screen
  • Doomsday: sub attack is much lower than for DD

Destroyers (DD)


  • Most cost-effective screen
  • Excellent sub detection and attack


  • Short combat range

Task Forces

Carrier Task Force (CTF)

The Carrier Task Force (CTF) is quite different to the Surface Action Group (SAG). The CTF relies on driving its enemy from the area rather than killing its enemy. When properly used, a CTF is the most potent surface combatant group in the game.

CTF Composition

A strong composition for a CTF, considering a fleet size of 18, is as follows:

  • 6 CVs depending on the level of enemy resistance expected
  • 2 CVLs as damage soaks against surface ships in bad weather
  • 10 DDs to provide screens for the capitals, defence against subs and enemy air

Some players advocate using CAs instead of CVLs as damage soaks. For HoI2, this was the ideal soaking ship, as the CVL didn't exist. For Doomsday and Armageddon, however, a CVL is better suited, as it has a far better detection/visibility ratio than a CA.

Surface Action Group (SAG)

The Surface Action Group is quite different to the Carrier Task Force (CTF). The SAG relies on killing its enemy, rather than driving it from the area. A SAG is a task force of surface ships whose primary duty is to attack and sink other surface ships. It relies on Gun Ships to do direct damage to the Strength of other ships. A SAG also excels in its secondary duty of providing Shore Bombardment support to friendly land units fighting in coastal areas.

Fleet Composition

Considering a fleet composition of 18 ships, the strongest SAG is as follows. This model can be followed with less powerful SAGs, by replacing the SHBBs with BBs for a still potent force. Using BBs is more cost effective, since 3 BBs can be built for every 2 SHBBs. Finally, Heavy Cruisers (CA) can be used, for a cheap, yet still reasonably strong SAG.

Zerg Fleets

Zerg fleets are considered a gamey exploit of the flawed naval combat engine. This exploit was tested and made popular by Blue Emu, and features a fleet that uses a single Combat Range as a way of ensuring as many guns as possible are brought to bear on the opposing fleet. Zerg fleets are based on the simple fact that the naval model means that the more ships in combat, the more damage can be done. The Zerg fleet is feasible only if it can close in on its preferred range. Before the Armageddon 1.3beta patch, this was possible due to the amazing strength of the light carriers which ensure closing to within range of the shortest range capital vessel in the fleet. With the Armageddon 1.3beta patch, CVLs still help in closing the range, but no longer magically do so. Having up-to-date doctrines and good leadership and positioning is now impervious for a zerg fleet. Zerg fleets have two basic forms. The original form is less gamey, while the DD zerg is widely considered an exploit.

The Original Cruizerg Fleet
  • 5 (1938) Heavy Cruisers (CA)
  • 2 Light Carriers (CVL)
  • 11 (1938) Light Cruisers with fire control (CL-FC)

For a total of 18 Ships.

This Cruizerg is effective because the light cruiser screen vessels, when equipped with fire control, have the exact same firing range as the heavy cruisers. A typical BB SAG would have only the Battleships in firing range, while all other naval vessels would simply absorb damage but not otherwise participate in the battle. Thus, when the Cruizerg meets a BB SAG, the Cruizerg is actually more powerful, not to mention twice as efficient in IC cost.

DD Zerg Fleet

A zerg fleet based on destroyers is an example of hopelessly gamey tactics, but is certainly an effective killing machine. Usually, plain DD-fleets can close in to 5km range by the second hour of battle.

  • 60 - 90 DD
Cruizerg Fleets for Doomsday

Doomsday lacks naval brigades, so one has to use obsolete vessels to make the strategy work. There are two setups, one involving either all CA-IIs and CL-IVs or a mix of CA-IIs and CA-IIIs, the second consisting of all CA-IIIs and CL-VIs. Note that at least one of the CAs needs to be of one level lower than the CLs, so that their range is identical. CVLs are necessary as well, to ensure the fleet will close with CTFs. In Doomsday, CVLs can still magically close the combat range to their preferred range. This was rectified with the Armageddon 1.3beta patch.

Early-Game Composition
  • 2 CA-II (Absolutely necessary for the strategy to work to allow CL-IV to be in range since the CVL will go to the lowest ranged capital ship)
  • 4 CA-III (CA-II will work here as well)
  • 2 CVL
  • 10 CL-IV
Late-Game Composition
  • 6 CA-III
  • 2 CVL
  • 10 CL-VI

Hybrid Fleet Composition

If you want something with the shore bombardment power of the SAG and battle prowess superior to the the cruizerg, look no further. I've taken down other human players using cruizerg fleets with this, but it can still be taken down by destroyer zerg fleets.

  • 4 BB-VII-FX (SHBB)
  • 2 BB-III (no FX, important*)
  • 2 CVL
  • 10 CL-IV-FC(2)

'* BB-III and CL-IV-FC (with an upgraded FC) both have a range of 34, if you put a FX on the BB-III's, the light cruisers will not be able to fire on the enemy. This is not an issue when putting FC's on the SHBB's since they will be firing as soon as they are in range and pack a much bigger punch.

For later naval warfare:

  • 4 BB-IX-FX (SHBB2)
  • 2 BB)IV (no FX, same reason as above)
  • 2 CVL
  • 10 CL-VI-FC(2)

The engagement range here is 36 and has better firepower.

Marine Amphibious Force (MAF)

A Marine Amphibious Force is a limited Surface Action Group(SAG) with Transports (TP) attached to it for the purpose of ferrying troops and executing amphibious assaults. Shore bombardment will automatically occur during an amphibious assault by all capable ships in an adjacent sea zone.

Amphibious assault mission: This must be issued when the fleet is already located in its home port. Otherwise, it will likely result in the entire fleet returning to its home port. Alternatively, troops can simply disembark from the transports and attack. This only works for games up to Armageddon 1.2. For the Armageddon 1.3beta patch, disembarking from transports into enemy territory is no longer possible. Leaving transports in the region is important for early assaults, in the event of defeat or retreat, troops can retreat to the transports.

MAF Fleet Composition

Three philosophies are debated, currently.

  1. TP-only fleets: This playstyle argues that TPs should be left in TP-only fleets. The reason is that TP-only fleets have a optimal combat range of 450+km and then flee. Adding even a single warship will decrease this and let the TPs participate in combat, where they can only lose.
  2. CV-protection: Followers of this idea argue that adding a CV to the fleet will put the fleet at a distance to all surface fleets that do not contain carriers, thus protecting the TPs better than if they are sent out alone.
  3. Surface fleet: This is the "old-school" version of a MAF: combine your TPs with a sufficiently strong SAG to defend the transports.

Anti-Submarine Warfare Group (ASW Group)

An Anti-Submarine Warfare Group is a group of ships whose role is to hunt and sink enemy subs. Since the primary anti-sub vessel is the DD, this is the core of any ASW group. An escort carrier is also very deadly for subs. In HoI2 and ARMA, ASW fleets are quite useful, while in Doomsday, the ASW fleet was largely ineffective. The Armageddon 1.3beta patch has solved all remaining bugs with the ASW mission order, and it will now work as intended. Especially late-game, it is very deadly.

ASW Fleet Composition

Best is smaller numbers for increased range:

  • 2 CVLs
  • 2 CLs
  • 4 DDs (possibly with ASW naval brigade)

Submarine Wolfpack

Any group of submarines that includes no surface ships forms a wolfpack. Large groups are good for naval combat in HoI2 and ARMA, but considered ahistorical and gamey.

Convoy Raiding

When using submarines to create pickets, Subs should be positioned on the high seas, as far as possible from enemy Air and Naval bases, in order to force the enemy to come out and fight the player's subs under conditions that give the enemy no advantage (no Air support, no Air spotting, no quick reaction from supporting forces in a nearby Port).

The other requirement for Sub-fleet positioning is that together they must form a complete blockade-cordon, cutting the enemy capital from all possible convoy destinations. The AI will automatically shift the route of a Convoy that has suffered U-Boat or Air attack... but this won't help it at all as long as all possible Convoy-routes are covered by subs.

Doomsday and Armageddon

In Doomsday, submarines were significantly reduced in power, so much so that many players called them worthless. In an infamous thread on the Paradox forums (Blue Emu's Are Submarines Worthless), it is shown that a German wolfpack strategy can be highly devastating to English supply convoys, effectively destroying their ability to fight overseas. With a 63 Uboat fleet (1938 model), Blue Emu tallied the following losses for the UK in 1939:

September : 227 Convoys, 27 Escorts
October : 149 Convoys, 33 Escorts
November : 117 Convoys, 13 Escorts
December : 161 Convoys, 26 Escorts

This accounted for nearly half of the British convoy fleet in the first four months of war. While England's home supply stockpile was not affected due to pre-war build up, their armies overseas (North Africa, India, and South East Asia) were rendered out of supply. This means relatively easy victories for Italy and Japan. Further, trade efficiencies drastically suffered:

Trade with Norway, Sweden and Latvia is 100%.
Trade with the USA, Mexico, Chile and Panama is 57.9%.
Trade with Saudi Arabia is 51.8%.
Trade with Yugoslavia is 51.1%.
Trade with China is 26.0%

Beginning with Armageddon 1.2, players have reported large success in using large sub stacks against surface ships, especially in the early war years.




Positioning is the term for how the game handles the starting conditions of a sea battle. This section is based on some gross simplifications, because positioning is quite complex, far too much so for a number-crunching examination of it. Instead this part of the guide focuses on tendencies observed from actual game experience with the goal of illustrating just the factors within your control that you need to pay attention to, and their actual effects on naval combat and the tactics you should use in dealing with it.

Basic facts:

  • The higher your fleet's positioning, the more chance that your ships will begin the battle in position to fire on the enemy and the greater chance that your shorter ranged screening ships will be in position to help defend the heavies;
  • The lower your positioning, the more chance you will have to spend one or more rounds maneuvering before any of your ships can even shoot at anything, and the less chance your screen will be in position to defend your more valuable capital ships.
  • When there is no real positioning advantage, the opposing fleets will tend to begin the engagement separated by a distance approximately equal to the range of the longest-ranged ship in the entire engagement and both sides' screens will be slightly out of position but not badly so.

What affects Positioning

  • Suprise
Having surprise on your side increases your positioning and lowers your enemy's, which will adjust that starting distance towards the range of the longest ranged ship in your own fleet and put the enemy's screens further out of position allowing you to concentrate fire on the more valuable enemy targets.
  • Fleet Composition
That said, when dealing with a 30-ship fleet heavy with BBs, don't waste time trying to tweak your fleet composition to improve your chance of surprise. You have no chance anyway, so instead gear your composition to best deal with the inevitably poor positioning it will have to endure most of the time. Generally this means including extra scorts who can absorb damage for your heavies and provide extra air defence.
  • Leadership
Leadership also plays a role in positioning, with higher leadership values and certain traits imparting bonuses to positioning, but these are eclipsed by fleet composition and surprise. I cover these further on in the leadership section.

Like HoI 1, surprise and positioning are affected by yours and your enemy's detection and visibility values. The higher your detection and the lower your visibility, the more likely it is that the surprise equation will work in your favor and give you advantageous positioning. So obviously the main trick to improving that situation is to include a few subs in your important task forces, since they have decent detection and VERY low to practically no visibility. A secondary tip is to not include more line ships than are needed for the mission, since every surface ship you add increases your fleet's total visibility. The only exception is the CV, which has a correspondingly high detection value to offset its high visibility, and thus does not really net you a disadvantage when it comes to surprise. No other line ship has a sufficiently high detection rating to offset its visibility, not even the CA.

Positioning is also where capital and screening vessels come into play, not to be confused with the terms line, principal or escort. For purposes of positioning, the game divides surface combatant ships into two classes: capital ships and screening vessels. CLs and DDs are the only ships which count as screening vessels. All other surface ombatants, from CAs on up, are considered capital ships. The game applies a positioning penalty to a fleet if the number of screening vessels is not equal to or greater than the number of capital ships. This is to simulate the handicap such a fleet will suffer due to its lack of picket ships to perform early detection and combat support. Transports and subs, since they are not surface combatants, do not count in any way in this regard. They neither help nor hurt your fleet's capital ship to screening vessel ratio. So when considering fleet composition, first figure out what mix of surface combatants you need to do the mission, then make sure there are not more capital ships than screening vessels, and last add whatever subs or TPs you need involved in the mission.

Combat Range

Combat range is a factor in determining positioning. Each fleet has an optimum combat range it wants to achieve when entering combat, and if it achieves surprise it will have a good chance that its positioning will be high enough to start the battle at that range. For example, Transport Fleets will have their goal to escape, so their optimum range is 450 km. If this range is achieved, the transports will be able to retreat without taking damage. Meanwhile, a CTF needs to be in range for its planes to strike, and yet out of range of capital ship heavy guns. Finally, a SAG needs to close distance as much as possible in order to unleash all its firepower.

Given no surprise on either side, imagine a 15-ship CTF entering battle against a 30-ship BB SAG, with both fleets led by comparable leaders and composed of medium tech vessels. Since neither side is advantaged by surprise, the longest ranged ship on either side will tend to set the initial engagement distance. That will of course be the CVs whose combat range will likely be around 180km at medium tech. The next longest ranged ship is the Super Battleship, which has a range of approximately 40km. That means the BBs will have to close the distance by about 140km before they can even shoot back, all the while being bombed by the enemy planes. In HoI2, CVs ruled the seas for this reason, with the only exception of night battles and bad weather. Starting in Doomsday, however, balance was restored: with the introduction of light carriers, it became possible for an SAG with CVLs to close distance.

Combat Range in Naval battles has an optimal value. This value is believed to be calculated as described below

  • CV is the highest class in calculating optimal range.
  • Capital Ship or CVL is the second highest class in calculating optimal range.
  • Screen Ship is the lowest class in calulating optimal range.
  • Unique class's
    • Submarine ONLY fleets will attempt to be at 90% of the maximum range of the shortest range submarine
    • Transport ONLY fleets will attempt to be at 450+ km and then flee.

Optimal Range will always be 90% of the maximum range of the shortest range of the highest ship class.

i.e. If you have two Capital Ship's in a fleet. One with a range of 30 and the other with a range of 28, the optimal range will be 90% of 28.
NOTE, Range of a lower class is ignored. If you have a Capital Ship in a fleet with a range of 28 and the rest of the fleet is Screen Ship's with ranges of 32 the optimal range will be 90% of the range of the Capital Ship (i.e. 90% of 28) The range of the Screen Ship's is ignored.


Leadership has three main affects on your naval operations as do leader traits, and these can be very critical so care should be taken to consider all of these when assigning leaders.

  • Command limit -- a leader's rank determines how many ships he may simultaneously command without suffering command penalties. This works pretty much like land combat command limits except that the number of units allowed is different per rank level, ranging from 6 to 30 instead of from 1 to 12. Also, HQs have no effect on naval command, so there is no naval equivalent of the HQ unit's "doubling" effect on command limits as seen in land combat. When a leader ends up in a position where he has more ships under his command than his command limit allows, all ships beyond the limit get no benefits from his leadership traits and suffer a 25% penalty to their effectiveness to boot. Finally, just like land combat, one leader must command all the friendly forces in a particular battle, even if they come from multiple fleets, or even from different allied nationalities.
    • Transports & Large Fleets: Unlike HoI 1, there is no free ride for Transports. Every TP in the fleet counts against the command limit of the fleet's leader. There is a loophole here, though. Since the game engine ranks all combat vessels ahead of TPs when it arranges them for effectiveness calculation, the TPs will be the first ones to get the "over command limit" penalty of 25% and lose the leader's bonuses. And since the TPs aren't fighting in the battle anyway, this means your combatants can get away without the penalty as long as their total number not counting the number of TPs is within the leader's limit. Thus, a fleet of 30 combatants plus 30 TPs led by a Grand Admiral (command limit 30) would suffer no penalty to its combat effectiveness from leadership once engaged. There is a catch, of course: those TPs would not benefit from such traits as Spotter or Blockade Runner and would severely handicap the fleet's positioning value as a result, plus non-TPs ships over the limit would still increase the stacking penalty for all ships in the group (see stacking, below); so you don't want to play fast and loose with the command limit. Finally, large task forces are very likely to be surprised, and thus suffer positioning penalties.

Also, leader traits aside, a task force that large would be pretty much impossible not to surprise, so would constantly be at the short end of the positioning stick. Bottom line: if you don't need to exceed the command limit of a leader for some overriding reason, then don't. Remember also that just like land combat, units suffering the penalty are likely to break early due to org losses and force the entire fleet to retreat early as a result. And don't forget that,

  • Leadership skill and positioning -- The higher a leader's skill rating, the better chance his force will enjoy better positioning at the start of a battle. This effect is eclipsed, however, by detection and visibility. For example, a skill 5 leader commanding a fleet of BBs will still be disadvantaged in positioning when encountering a skill 1 leader commanding a couple of CVs and DDs. Fleet composition is far more important in that regard. But don't ignore it, either!
  • Leadership skill and combat effectiveness -- this functions just like land combat. The higher the leader's skill, the more effective his ships will be in combat once engaged. Again, however, this is often eclipsed by positioning. The same skill 5 leader commanding a fleet of BBs will not get full use of his effectiveness bonus when a skill 1 leader commanding a CTF engages him from a range of 200 miles, because his ships won't be able to shoot back anyway. They will, however, enjoy a better chance to defend themselves from the air attacks while they move into range of, or retreat from, the CTF. So leader skill is still important, but by itself won't save you from bad fleet composition.
  • Leader traits -- Because surprise is now handled pretty much the same for everyone as simply a component of positioning, the leader traits are now more universally useful. In HoI 1 the Spotter and Blockade Runner traits were most effective for CTFs and MAFs, for example, but are now useful to any fleet that has a need to improve its positioning value. So just evaluate your fleet's mission and composition, and then assign the leader with the skill and traits that best augment its ability to carry out that mission. There is a basic principle of warfare: always support strength, never support weakness. In this context that means don't bother assigning a Blockade Runner to command a force with pitiful positioning values. His strength is wasted there because it will never overcome the positioning deficit caused by the fleet's composition. If a fleet is composed in such a way that it is going to suffer from a severe positioning handicap, assign a leader with skill and traits that will improve its ability to cope with that positioning handicap, like Expert Tactician. If the fleet is marginal on positioning but is on a mission where it requires good positioning to ensure success, like ASW or interdiction missions, then assign a leader with Spotter and/or Blockade Runner traits to give it that positioning boost it needs.


This is the only area in which TPs get a free ride. Stacking penalties, not to be confused with command limits, apply to any naval force in involved in combat that contains more than 2 non-transport vessels. The penalty takes the form of -1% effectiveness for each non-TP ship beyond the first two. This penalty is applied to the entire fleet. So a fleet with 10 combat surface ships, 2 subs and 18 transports would suffer a 10% effectiveness hit when engaged in combat (12 non-TP vessels minus the first two as freebies = 10). However, that fleet would suffer no command penalty as long as it was led by a Grand Admiral since the total number of vessels was not greater than his command limit of 30. On the other hand, a force composed of 30 combatant vessels would suffer a 28% stacking penalty, in addition to any command penalty that would result if it was led a leader of lower rank than Grand Admiral. Like command limits, the stacking penalty takes into account all friendly forces present in the battle as one total, even if they come from several different fleets, or even from different allied nationalities.


Once a battle is over it is time to take a look at your forces involved in the fight to see if further orders are needed. Usually one of three things will be the logical next step:

  1. If your ships took significant damage or org losses, return them to port. Ships at sea do not repair, and ships in port reorg more quickly. Be sure the port has capacity at the moment, though. A 10-capacity port that already has 12 damaged ships in it is going to greatly slow the rate of all ship repairs done there if you go and add another 12 damaged ships to its workload. Ships do not need to return to the port they are based at to repair, so just give them a move order to somewhere else nearby that has decent free port capacity. On a side note: port capacity is not terribly important in deciding where to base your ships, unless you want to be able to leave them in automatic mode executing the same order for a very long time and periodically returning to port on their own when they need to. Port capacity really only affects repair and reorg rates, not supply ability. For example, a port with a capacity of four could be used as the home base for 3 fleets totalling 45 ships, but as long as only four damaged ships were present in port at a given moment they would be repairing at full speed.
  2. If the enemy retreated and you have a combat-ready formation present, pursue the enemy. An arrow will appear on the enemy fleet's icon showing which way it is retreating, so give your combat group a move order in that same direction. If your ships are fast enough they will arrive before the enemy reaches that seazone, or at least before he can leave it, and you can pound him again. Lather, rinse, repeat.
  3. If you don't need to repair and you need your ships to continue what they were doing before the combat happened, then do nothing. They will automatically continue executing their previous orders.