Bram's Naval Warfare Guide

Introduction. Much of the Rome II world is dominated by water. Use of sea areas for offense, defense, trade, and military transport is an integral part of expanding (and defending) a successful empire. Fleets can be used as superbly effective "force multipliers" when carefully built and employed.

Philosophy. I’ll be upfront; Rome II naval combat is not well-designed. Ancient fleets relied primarily on ramming and/or boarding tactics. Doing so in Rome II, however, is a recipe for unnecessarily high losses and even perhaps battles lost by a heavily-favored player force. It is extremely common for players to discard naval combat altogether, perceiving it as “broken” and simply not worth the investment.

Fleets, however, can be quite effective, albeit in a thoroughly ahistorical way. The key is to take advantage of long-ranged missile capability: artillery. Unlike land units, there are two ways to damage/destroy an enemy unit at sea. First, one can attack the ship’s crew, either killing them all or inflicting enough losses that they rout. Second, however, and unique to naval combat, one can attack the enemy ship itself, which has a separate health pool. Using artillery, one can completely destroy an enemy fleet at long distance, even while inflicting relatively light personnel casualties. AI fleets typically do not build very many artillery vessels: an artillery-strong player fleet becomes virtually unbeatable at sea.

I will note that this pertains specifically to naval combat against the AI during a campaign. This strategy will not work against the AI in a custom battle, because the budget system will allow it to field a much stronger fleet than is encountered during a campaign.

Ports. There are two basic naval construction lines for Roman and Hellenistic factions: the military line and the shipwright line. Barbarian and Eastern factions have only one naval port line.

https://i.imgur.com/OFO20gE.jpg
Roman Port Development Tree

https://i.imgur.com/mC4ZcMu.jpg
Hellenic Port Development Tree

https://i.imgur.com/bMriMg0.jpg
Barbarian Port Development Tree

https://i.imgur.com/PXxDnuv.jpg
Eastern Port Development Tree

Military Wharf line (Rome and Hellenic). Can only be built in provincial capitals. Without going into faction-specific variables, the military port line generally builds larger, stronger, higher-health ships. For Rome and Hellenistic factions, the military line is required to build artillery-equipped vessels. Comparable to a faction’s “main-line” land barracks.

Shipwright line (Rome and Hellenic). Can be built in minor settlement ports as well as capitals. Generally builds lighter, lower-health ships, primarily focused on missile-unit support vessels. Note: unlike land-unit barracks, a shipwright built in a minor settlement can only be developed up to Level III. In most cases, however, this is not particularly important. Comparable to a faction’s “aux-line” land barracks.

Harbour (Barbarian) and Military Pier (Eastern) lines. These factions can only build one naval port line, and do not enjoy quite the variety of vessels as Romans or Greeks. These factions do, however, have artillery-equipped and assault ships available.

Recruitment – Ship Types. There are many faction-specific permutations of vessels available, and the port types required to build these ships. All factions, however, have access to three basic ship types.

Assault Ships. Manned with melee/spear infantry crews. Primarily useful for close-combat, boarding enemy vessels. As noted above, this type of battle should generally be avoided, so I recommend a small proportion of such vessels, and entirely feasible to ignore assault-vessel recruitment entirely.

Missile Support Ships. Manned with missile troops. Some of these vessels also mount a scorpion (small anti-personnel artillery). All of these vessel types are serviceable; one should prioritize range and hull strength when choosing between different varations of this type. In other words, go for archer-manned ships over javelin-manned ships. It is also important to have a fire-projectile capability, as this adds the possibility of fire damage to enemy hulls.

Artillery Ships. Small crew, mounts an onager or ballista. These are the ship-killers, and one should have a very high proportion of these; up to roughly half of the fleet, at very least one-third at a minimum. As with their land counterparts, there are range/damage/fire-rate tradeoffs when choosing between ballistae and onagers. Both types are effective in the role, but I tend to favor ballistae for their longer range; this can become particularly significant when bombarding a port settlement.

Stances.

https://i.imgur.com/FQ2H3zp.jpg

None. The default stance. No particular benefits or disadvantages.

Double-time. The maritime equivalent of “forced-march”. Extends movement range. Cannot initiate battles. Substantial morale penalty if attacked. Worth noting, however, that there is no “ambush battle” at sea, so getting attacked in this mode isn’t quite as dangerous as on land, particularly if one designs the fleet to maximize ranged combat instead of close-quarters ramming/boarding.

Patrol. Fleet remains stationary, and combats piracy in the sea zone where the fleet is located, boosting trade income by decreasing the piracy penalty. Similar to land fortification, the fleet gets a defensive buff and extended reinforcement range. In practice, this stance is largely worthless, adding only a few coins; hardly noticeable. The defense and reinforcement buffs likewise are less useful at sea. If one is going to park a fleet for a while, probably more beneficial to place it inport for added military-presence public order bonus.

Raiding. Fleet raids the sea zone in which it is currently located, boosting income. As on land, fleet upkeep is reduced and there is a morale buff, but this stance is also of dubious benefit. Most sea zones carry trade from multiple factions, often far more than is typical in any land province. Many of these factions will not be at war with the player. Raiding is indiscriminate, and will incur diplomatic penalties with everyone trading in that sea zone. Like land raiding, this stance also reduces fleet movement range.

There is no “ambush” stance (or rough equivalent) at sea.

Combat. The basic principle for all engagements is to maximize long-range artillery fire, and minimize close-quarters ramming/boarding combat. Build your fleets with about half artillery, half missile-support vessels. Use the missile support ships as a front-line “screen” to protect the artillery. If you do take losses, you’ll take them in the screen, among the (usually lower-cost) missile ships. Following this basic strategy will generally work well in any battle.

https://i.imgur.com/jVQlYUJ.jpg
A typical fleet composition using this concept. Adding just a few (2-3) assault ships can sometimes be useful in capturing port settlements

https://i.imgur.com/GOKKIwM.jpg
Typical, simple deployment. The missile ships forward serve as a screen to protect the artillery vessels.

That said, some comments about various types of battles:

Vs Naval Fleets. The AI enemy will have high-strength vessels, and several of their ships will survive artillery fire long enough to close and engage with your fleet. Expect a few losses among your screening units. From the start, prioritize several ships’ artillery fire on their admiral’s vessel, as it is almost certainly the highest-hull-strength unit in their fleet, and of course because of the morale de-buff which will occur when his ship is sunk.

Vs Transports. Regardless of unit strength, all land-unit transport ships have weak hull strength. It is entirely possible to sink all enemy ships before they can even close to engage with your screen. The embarked enemy land units, however, are larger than naval counterparts; if the enemy DOES manage to close with your ships and board, he will have far more troops in these battles. For this reason, it is even more important to avoid close-quarters combat when fighting against an enemy transport fleet.

Vs Minor Settlements. An unsupported fleet composed exclusively of missile and artillery ships IS capable of capturing a minor port settlement, in most cases.

Send your missile-support ships close to shore, primarily to ensure visibility on as many garrison units as possible, but also to threaten an imminent landing without actually doing so. Without a land threat to worry about, the AI will usually prioritize troops to defend these potential landing zones, bringing them within range of your own missile troops. This is the main reason that I advocate using archers rather than javelin troops for a fleet’s missile-support screen.

Use fire or whistling-shot abilities to maximize morale de-buff on the enemy units; your archers’ goal is to help break morale, rather than outright maximizing casualties.

Meanwhile, use your artillery to bombard garrison units. You will usually have to keep a close eye on all your artillery ships, and continually update targeting orders. Reason; seagoing artillery, especially ballistae, have much narrower firing arcs than their land counteparts. If visible enemy units are outside the firing arc, the artillery ship will just sit there and not shoot at anything, even with “fire-at-will” mode enabled (this is also true in the sea battles; continuously review your artillery’s status and ensure they’re firing at something).

In most cases, your fleet will be able to completely rout the entire garrison with missile and artillery fire, enabling capture of the port. This is true even if the port is defended not only by a garrison but also a field army. Capture of a minor port, can become problematic under two conditions:

First, some port maps feature a city center some distance away from the waterfront, and sometimes at higher elevation. The challenge becomes spotting all garrison units in order to fire upon them. In these cases, it sometimes becomes necessary to land a few units in order to gain visibility. For these cases, it can be useful to include a few assault ships with strong infantry, particularly if one is building a fleet focused specifically toward port capture rather than at-sea dominance.

Second, ammunition capacity may be limited. When dealing with a large garrison bolstered by a large field army, the sheer number of enemy units, regardless of quality, can strain ammunition stocks. It is possible that you will simply run out of ammo before the last few units break. This is not a disaster by any stretch. Simply retire. You will “lose” the battle, but your ships are intact and have taken few personnel casualties. Meanwhile, the defenders have taken huge losses from your artillery. Just attack again on the next turn. Or alternatively, the town’s defenders are now much easier prey for any land force you may have in range. Here again, if you run out of ammunition but have 3 or 4 assault ships with good melee troops in reserve, they can now land and perhaps easily wrap up the few remaining damaged enemy.

Vs Walled cities. Unless the defending capital is underdeveloped and/or has an unusually small garrison for some reason, in most cases an unsupported fleet will have a difficult time capturing. I would advise against trying to do so.

An artillery-heavy fleet, however, can be of enormous help if supporting a siege assault by a land army. Pick an assault point near the shore, where seaborne ballistae will be in range of the city’s defenses. Use the fleet artillery to destroy missile towers and open wall breaches. The fleet will have so many ballistae that they can pulverize an entire section of wall, rather than simply open a narrow breach. In this way, one can create nearly “open-field battle” conditions in a localized area, greatly aiding city capture and minimizing losses.

thanks i have been looking like cracy for a good guide for naval part i usually autoresolve all navalbattles as i loose way too many ships manualy and this will help alot trying this when getting home :D

Goot job Bram! :bow:

Perhaps you could elaborate further on the Navy versus Navy combat. How do you manage to manuever your fleet to keep them out of boarding range while still able to inflict damage?

I have tried your half artillery half missle make up and I still find myself losing losing 3 quarters of my fleet to pure javelin fleets. Even though I win the casualty rate is too high. The opposing fleets cuts through the missile screen (javelins as I do not have access to archers) like butter and then manage to kill half of the artillery before finally giving up.

No, I don't try to maneuver to stay out of boarding range. Ships just move too clumsily for that to be effective.

Are you micro-ing the ballista ships' targets closely enough? You do still have to do that. Just leaving them on "Fire At Will" doesn't cut it. A major reason is their narrow firing arc, and they won't turn the vessel to keep something in range. So you have to continually cycle through all your ships to ensure they're firing.

On the other hand, no problem to leave your jav/archer screen on Fire-At-Will, as they have a 360deg firing arc.

If you have half your fleet (i.e., 9-11 or so out of 20) composed of ballistae, AND they keep firing effectively throughout the engagement, then a 20-unit fleet of "starter" javelin raider type ships isn't going to inflict 75% losses.

Quote:

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Originally Posted by Bramborough

No, I don't try to maneuver to stay out of boarding range. Ships just move too clumsily for that to be effective.

Are you micro-ing the ballista ships' targets closely enough? You do still have to do that. Just leaving them on "Fire At Will" doesn't cut it. A major reason is their narrow firing arc, and they won't turn the vessel to keep something in range. So you have to continually cycle through all your ships to ensure they're firing.

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I was setting the initial target but not really going back afterward figuring they would move to the next one. Tried a more closely managed battle and the results were better. Still need work at effective targeting but I should get the hang of it soon.

just tryed it my self with egypt and i only lost 1 ship and that was a skirmisher the rest of the skirmisher were damaged but alive

you bram is a genius :D (guess how my other fleets are composed like ;) )