A Guide to Warfare in Imperator: Rome (1.3 Livy)

If, like me, you simply cannot get enough of Paradox Development Studio’s grand strategy titles, then you have likely been playing a lot of Imperator: Rome. Though the game synthesizes mechanics gleaned from a bunch of the studio’s previous titles it is first and foremost concerned with warfare – expanding your empire, and winning battles. Because of this, a strong emphasis is placed not just on strategic geopolitics, but also on the nitty-gritty tactical-level combat of your armies in the field.

Whereas in some other Paradox titles tactics can be safely ignored, in Imperator, they’re a fundamental component in your quest to stamp your name across the map. It’s not quite as impenetrable as some grognard fare, if you’re new to these kinds of games, the minutiae of the new tactical combat mechanics can be a bit daunting. If you need a primer, or just want to see what’s changed in the recent 1.3. ‘Livy’ update, we’ve got you covered.

The Fundamentals

Let’s start with the absolute basics before moving onto the meatier stuff:

  • Armies are composed of cohorts of 1000 men each and are built and replaced using your nation’s available manpower pool.
  • There are nine unit types: Archers, Heavy Infantry, Light Infantry, Camels, Heavy Cavalry, Light Cavalry, Horse Archers, Chariots, and War Elephants.
  • Each of these unit types has certain traits — like their maneuver and damage ratings — that make them useful in certain roles, such as cavalry in the flanks, archers as frontline skirmishers, and heavy infantry as the hard backbone of your reserve. Units will also deal more or less damage based on what type of unit they are fighting.

It’s worth noting that Imperator is extremely transparent, although it’s not always obvious. Pretty much everything you need to know to make informed decisions about your enemy can be found in tool-tips or other parts of the UI. For example:

  • You can see exactly how many cohorts other nations have recruited and how much manpower they have in reserve in the Diplomacy Screen.
  • The Warscore Screen will tell you how many of each unit type an opponent has.
  • By hovering your cursor over an enemy army, you can see what types of units they are comprised of, as well as their general’s martial skill.

Combat Mechanics

Imperator‘s combat system is broken down into 3 components: a primary frontline, a secondary frontline, and flanks. It’s similar to the system Paradox used in Europa Universalis IV, though much more streamlined for tactical customization. Here’s how that system plays out in practice: 

  • Only the units in the Primary frontline and the flanks can attack.
  • Units attack the enemy directly across from them at first, and then, as units flee or are killed, they can attack other units in the line based on their maneuver skill.
  • Flanking units typically have a high maneuver, allowing them to attack far into the primary frontline after the enemy flank has been dealt with.
  • Once units from the primary frontline are removed, units from the secondary frontline, acting as a reserve, will move into the line to take their place.
  • Both the size of the flanks, as well as which unit types will be placed in each of these roles can be modified in the Army Interface, allowing you to experiment with the different roles once you have a firmer grip on combat mechanics and army composition.

Additionally, discipline, morale, leader skill, and terrain all impact this basic structure. A die roll takes these factors, as well as your unit types and modifiers and applies them to determine how much physical and morale damage is being dealt, with a new roll happening every five days. Having a Leader with a high martial skill will give buffs to your rolls, whereas adverse terrain effects can give a debuff. Even if there is some hard math going on under the hood, you can get by with an intuitive understanding of some military basics.

For example, you don’t need a graduate degree in mathematics to know that you should avoid letting incompetent generals attack with underpaid units over rivers.

Army Composition, Traditions, and Tactics

The real nuts-and-bolts of Imperator‘s tactical gameplay lies at the intersection between the various combat mechanics and each nation’s unique strengths and weaknesses. The trick to crafting a coherent army composition is to take into account how these systems react to and play off one another. So, how do you know what composition to use? Most often, this will be determined by three factors: resources, traditions, and tactics.

Army Composition: Resources

At the most basic level, resources will determine what units you can recruit. To build war elephants, for example, you will need access to an elephant resource tile. This effectively locks certain unit compositions away from certain nations until they expand enough to acquire these resources. Strategic resources like iron, steppe horses, camels, or the aforementioned elephants will be highly sought after, and will likely funnel your nation’s army composition in a certain direction based on what you have available to you.

Army Composition: Traditions

Equally as important as resources is your Military Traditions. There are seven unique tradition trees, each with three branching paths comprised of eight steps, representing broad ideological developments within a culture group. These provide bonuses to different unit types, unlock special military abilities, and some even grant access to unique tactics for your army to use. Much like the scarcity of resources, the bonuses provided by these military traditions will shepherd you towards some types of units and away from others. Do your traditions give significant buffs to cavalry? You should probably consider using a cavalry-heavy force with wider flanks. Tons of Elephant buffs in the tree you chose? Maybe a meatier shock-focused force is right for you.

Army Composition: Tactics

The next factor to consider when composing an army is tactics. There are ten tactics that you can select for your army: five basic (Shock Action, Envelopment, Skirmishing, Deception, and Bottleneck) and five that are unique to specific military tradition trees (Triplex Acies, Hit and Run, Padma Vyuha, Cavalry Skirmish, and Phalanx). The old Sun Tzu maxim “if you know the enemy and know yourself, you need not fear the result of a hundred battles” holds especially true here as these tactics operate in a Rock-Paper-Scissors fashion with each tactic of the ten being good against two, bad against two others, and neutral against the rest.

If you’re having trouble finding out which tactics to use, the tooltip on the left of each bar shows what the percentage of effectiveness is for each tactic option based on your current army composition, while on the right of the bar it shows what tactics each particular type is good or bad against. Of course, Combat is not only knowing what tactics to use, but also knowing what tactics your enemy is likely using based on their current composition. Even if a tactic is lower on total efficiency, it may be more effective based on the enemy army’s composition.

Army Composition: In Practice

So, what does this look like in practice? Let’s use Rome as an example to see how these three factors come together to provide the framework of an effective army composition. Starting with the first factor, resources. Elephants, camels, and horse archers are all out of your reach from a resource perspective, so you likely won’t be able to use those, but Rome starts with access to iron and horses, so two types of cavalry, as well as heavy infantry are on the table.

In terms of traditions, Rome is part of the Italic military tradition, and within that tree there is a Roman branch that provides two bonuses to heavy infantry and one to light infantry. So you’re going to want to use mostly heavy infantry, with some light mixed in for skirmishing purposes, depending on your tactics, alongside some heavy cavalry, as the two starting tactics that buff heavy infantry — Bottleneck and Shock Action — also boost heavy cavalry.

Early on, you will be pulled towards the Bottleneck tactic, as it is effective with heavy infantry and cavalry, but the light infantry builds of your northern Gallic neighbors are likely using the skirmishing tactic, which is effective against that, so it may be a good idea to switch to shock action to neutralize. If you’re starting to expand south and begin fighting in North Africa and the Carthaginians are using shock tactics with elephants, switch over to the bottleneck tactic and change your composition accordingly. Once you have unlocked the Triplex Acies tactic from your traditions, switch your composition to a heavy infantry, light infantry, light cavalry combination to maximize efficiency and decimate skirmisher-reliant tribal states and the antiquated phalanxes of Alexander’s successors. Success in Imperator, much like Roman success in the real world, will depend on your ability to be flexible depending on what you know about your enemy.

Other Key Concepts 

Forts and Terrain

Operationally, Imperator uses forts and terrain to create a complex landscape to play out these engaging tactical battles. Forts exert a zone of control that disables movement through adjacent provinces, forcing armies to stop and siege before proceeding. Where the nuance comes into play is when you combine this feature with the impassable terrain that dots much of the map.

Creating bottlenecks through alpine passes or ambushing divided armies taking circuitous routes to get around forts is extremely satisfying and makes for some nail-biting gameplay. By navigating these mechanics wisely, even outnumbered armies can make the most of a strong defensible position to defeat a larger foe or stymie an attempted conquest. Don’t haphazardly deploy these defenses, though, as forts are an expensive resource to maintain and take up valuable building slots in your settlements. Be sure to tear down forts on pacified frontiers and replace them with more productive buildings.

Attrition, Manpower, and Mercenaries

At the macro level, your ability to keep the war machine running is going to be determined by your available manpower. It’s the key resource you will need to sustain your conquests. Unfortunately, in many provinces, harsh attrition can melt away your manpower in a matter of months. In theory, even in your home provinces, Imperator‘s brutally high attrition can prevent the kind of giant doom stacking that other Paradox strategy titles see, creating interesting tactical considerations in the process; however, by knowing how to get around these kinds of issues, you can avoid unnecessarily dividing your forces.

Some recent tinkering in the Livy update has made manpower even more vital. Maximum manpower caps have been shrunk and base manpower has been reduced by 50% from previous 1.2 levels. Along with a general decrease in starting army and navy sizes, this means that you have to make this already thinly-stretched resource go even farther. Avoiding unnecessary attrition is therefore a must for any competent strategist.

The best way to avoid attrition damage is to understand the new supply mechanics. While the 1.2 update added food as a new provincial resource that you need to manage, ‘Livy’ has added this mechanic to armies as well. To keep your stacks from taking unnecessary attrition, you can now rely on supply wagons that can be recruited as cohorts. These slow moving units are useless in combat, but allow you to bring stockpiled food with your troops to prevent attrition damage. Your armies can also raid food stocks from your enemies as well, allowing you to circumvent the brutal attrition of the ancient world.

What this means in practice is that you can maintain much larger stacks, so long as you are keeping up with your supply units. Make sure to keep these with your army to preserve your manpower. Doing so will allow you to focus the vast majority of your manpower on battlefield casualties, where it’s needed most.

The other key method to preserve manpower is to rely on mercenaries. Mercenaries are much more than a simple stopgap measure for wartime emergencies or auxiliaries to supplement your main army. The preciousness of manpower and the brutality of pre-modern attrition rates mean that they take on a much more pivotal role. In the early game, they will be less viable for smaller nations, as their high maintenance and disband cost (you need to pay them a lump sum at the end of their service) means that unless you’re playing as one of the large Diadochi kingdoms, chances are you won’t have the income to use them outside of extreme emergency situations. In the mid-to-late game, however, mercenaries will become much more vital for your war effort. As your state expands, trade and tax income should leave you with a healthy well of cash to dip into. By converting this cash into what amounts to a secondary manpower pool, you can keep up the pace of pyrrhic wars or conquer small states while your manpower pool is replenishing.

Mercenaries are spread out fairly evenly over the map, so there will likely be some in your backyard or your neighbors if you really need them. In the post-Alexandrian east, where the coffers are deeper, wars can often devolve into largely mercenary affairs, as each side tosses stacks at one another in order to overwhelm each other in the harsh deserts of the near east. If you find yourself on the wrong side of one of these conflicts, know that mercenary armies can be bought off and flipped to the opposing side of a conflict by being offered a large sum of money, which the original buyer can counter with a higher sum. This can allow you to significantly weaken an opposing enemy army right before an engagement or potentially end an important hostile siege. When it turns the tide of a close war, it feels so, so satisfying.

While the well-timed deployment of mercenaries can turn the tide decisively, it’s also worth noting that the last two updates have de-incentivized the overuse of this option. The introduction of supply and food mechanics slightly eases the necessity to rely on mercenaries to avoid Imperator‘s crippling attrition. As long as you bring sufficient supply units, it’s possible to keep your manpower from melting away.

Additionally, recent increases in the cost of buying and maintaining mercenary forces makes them much more costly than they were at launch. To purchase them, you not only need to sacrifice valuable gold, but also Military Experience, the resource that you need to get access Military Traditions. The Livy update has also increased the maintenance cost of mercenaries from 125% of normal units to a staggering 200%. While they are still a valuable part of the toolbox, you have to be much more careful with deciding when and where to deploy them.

Naval Warfare

Navies in Imperator operate in a very similar manner to armies. Much like your land forces, you have to consider traditions, compositions, and tactics. There are six kinds of ships, two of which, the Octere and Mega-Polyreme, are locked behind certain military tradition trees. Ships vary in stats, but generally they break down so that the weaker ships (Trireme, Liburnian) are faster and cheaper to maintain, while the stronger ships (Tetrere, Hexere, Octere, Mega-Polyreme) are increasingly slower and more expensive to maintain, but do increasingly more damage.

It’s important to note that Naval combat gives a bonus for the defender, incentivizing you to try and lure your opponent into a fight with you, rather than chasing down their fleet to engage. Like in land combat, units in the line will attempt to find a target to attack based on their positioning, which changes daily. Additionally, the basic stats for your ships can be augmented with both traditions and technology, so make sure you are investing in these areas if you’re going to be focusing on the sea.

When engaging in naval combat don’t forget to select a naval tactic based on your current composition. Naval tactics work in a similar rock-paper-scissors format to the army tactics, so if you understand how to wage war on land, you can apply those same concepts to the sea. Choosing the right tactic is both about knowing your current fleet composition and predicting what you believe your enemy to be using.

The End, and a Beginning

While Imperator: Rome will doubtless be built up with numerous patches and DLC, the base game rests on some really interesting tactical foundations. Paradox has been very proactive at fixing what was lacking at launch in its two most recent updates, such as naval combat and a lack of any kind of food/logistical mechanic for your armies. Coming from a studio that often ignores tactics altogether or abstracts them away, this is a really positive step forward, and hopefully is a sign of things to come. Even if you’re not someone with a penchant for optimizing army compositions or micromanaging field armies, there is a lot of fun to be had in learning to manage the nuances of Imperator‘s more combat-oriented gameplay.


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