Here, we’ll be talking you through the fundamentals of military playthroughs in Civ 6, including an explanation of the all new war conditions like Casus Belli, and likewise adding our own advice for the most efficient annihilation of your foe as possible. A quick note: we’ve refreshed out Civ 6 guides for the game’s launch on Nintendo Switch, but just be aware that they contain information regarding the Rise and Fall DLC as well as the base game, which means some things only apply if you have that DLC! Otherwise… crack on! Note also that this doesn’t mean simply reducing a city to zero defenses, as will happen after a successful siege or Nuclear and Thermonuclear bombing. You’ll need to actually place units into the defeated city and claim it for your own - before opting to keep or raze it - for that to count as a conquered city. What you do with it then is up to you. There are two ways to declare war on other civilizations in Civ 6, which we outline below:
Surprise War - Any kind of attack or declaration of war made without a prior Casus Belli or publice denouncement of your target will count as a surprise war. Note that you’ll need to wait at least 5 turns after denouncing your enemy for a non-surprise war to be possible that way. The warmonger penalty here is normally classed as ’egregous’, with those penalties increased by 50%. Casus Belli - Here, warmongering penalties are either reduced by 50% when classed as Moderate, or at standard levels when classed as Severe, and your options for the type of ‘just war’ you declare are expanded, depending on the circumstances.
Below are the various types of Casus Belli available, and how to unlock them:
Holy War - Requires Diplomatic Service Civic. Available when a power (civ or city-state) has religiously converted one of your cities. Warmonger penalties halved. Liberation War - Requires Diplomatic Service Civic. Available when a power has captured a city from one of your friends or allies. No warmonger penalty for liberating any of those cities. Reconquest War - Requires Diplomatic Service Civic. Available for declaring on a power that has captured one of your cities. No warmonger penalties. Protectorate War - Requires Diplomatic Service. Available for declaring war on a power that has attacked one of your allied city-states. No warmonger penalty for liberating that city state. Colonial War - Requires Nationalism Civic. Available for declaring war on a power that is two technology eras behind you. Warmonger penalties halved. War of Territorial Expansion - Requires Mobilization Civic. Available for declaring war on ap ower that borders your empire. Must have two of your cities within 10 tiles of two of that opponent’s cities. Warmongerpenalties reduced by 25%.
War Weariness - War weariness occurs in your cities in the form of reduced Amenities, and is increased if you went to war without a Casus Belli. The longer you are at war, the lower weariness will be (somewhat counter-intuitively), however war weariness will decrease much faster when you are at peace. Note that having particularly low Amenities for any extended period of time will cause rebel military units to spawn by your city-centres and pillage your land. Combat Stats - Each military unit in Civ 6 has a stat for Hit Points, Combat Strength, Ranged Strength, Bombard Strength, and Range. All units have 100 Hit Points, and are destroyed when they reach zero, but those Hit Points are decreased at varying rates according to the other relevant stats in question. In combat, a unit’s defensive durability is always measured in terms of Combat Strength, which is measured against the attacking unit’s Combat Strength (melee units), Range Strength (ranged units), or Bombard Strength (bombard units). Combat Stat modifiers - The stats mentioned above are modified by all kinds of factors in-game. Combat modifiers can be anything from terrain such as Hills and Marshland, which grant positive and negative modifiers for units on them respectively, to Promotion bonuses, fortification bonuses, and even leader-specific bonuses like Roosevelt Corollary, which grants his units a +5 bonus to Combat Stength when on their home continent. Experience and Promotions - All combat units gain experience from fighting enemy units, which will eventually lead to it levelling up and earning a Promotion, which grants various bonuses unique to the unit type. Fighting and conquering cities - Cities in Civ 6 have their own unique City Combat Strength stat, which determines it’s defensive strength. City Combat Strength is worked out by taking the Combat Strength of the strogest melee unit built by that civilization, minus 10, or by the Combat Strength of a garrioned military unit. City walls will grant it an additional ‘shield’ against all attacks other than Bombard type, with Melee attacks doing just 15% of their damage against walls and Ranged 50%. Cities also have Ranged Strength once equipped with walls, which can be used to attack units within two tiles, and is based on the Range Strength of the strongest ranged unit built by the civilization. Cities also gain additional City Combat Strength from each non-pillaged district it has, along with terrain and other standard combat modifiers. If all passable (so non-mountain) tiles around a city are occupied by enemy units or under their Zone of Control, that city is classed as under siege, whereby it will not heal automatically each turn as it normally would. Formations - New to Civ 6 is the ability to combine units into Corps, Armies, Fleets, and Armadas, meaning multiple units can be added together to take up only one tile. Corps and Fleets require the Nationalism Civic, which allows the forming of two units of the same type into one, whilst Armies and Armadas which contain three units require the Mobilization Civic. Pillaging - Pillagine is an excellent way to not only earn an extra income, but also damage the efforts and defences of your enemy. Pillagine a tile awards you plunder, which depends on the contents of the tile. Generally, the resources plundered correspond to the improvement, building or district in question, such as Science from the Campus or Spaceport districts. However, worth noting is that no Production can be gained from pillaging, with Production-based districts and buildings like the Industrial Zone or Mine awarding Science instead, and the Quarry awarding Culture.
If your lust for Civilization 6 knowledge is still going strong, expansion owners should take a look at our Civ 6 Rise and Fall guide hub which takes you through the basics of everything new, whilst we have dedicated pages on Governors and Loyalty, along with how to earn Golden Ages, Era Points and Era Score through Historic Moments, and a full list of new Civs in Civ 6 Rise and Fall and other DLC. Otherwise, our Civilization 6 guide, tips and tricks covers the essentials before you master early game, mid-game and late-game strategies. We also have tips on the new Districts feature, a Leaders list with their Traits and Agendas, plus the best ways to get Gold, Science, and Faith, how to win by Religious Victory, and how to earn the elusive Science Victory and Military domination victory. Finally, here’s the Culture Victory, Foreign Tourism, and Domestic Tourism explained in depth.
Plan your Corps, Armies, Fleets and Armadas around promoted units - Units grouped into Formations will all obtain the highest ranked promotion of those grouped. That means you can turn a single level three squad of Infantry into a 3-squad, level three bundle of death for minimal cost. Plan accordingly when preparing your military. Always pillage when attacking cities - Cities’ stengths are determined, in part, by the number of non-pillaged tiles around them. When laying siege then, you should pillage as much as you possibly can to lower their defenses (specifically the City Combat Strength stat) and make it far easier to attack. Save your nukes for certain situations - In other words, don’t nuke an area if you expect to pass through it, unless it’s with a quick rush to capture a defenseless city. Nuclear weapons will leave damaging radiation in their blast radius for 20 turns, with all units that end their turn in that zone taking significant damage. On the flip side then, nuke’s make great defensive weapons for holding choke points in particular. Be patient - A bit of a broad one, we know, but patience is certainly a virtue in Civilization 6. Wait until you have the numbers and the quality before launching an attack, as the tile-based combat system can completely ruin you if you trickle in. Picture the 300 Spartans holding off against the alleged 1 million Persians, and you’ll get the idea of what happens when you trickle into combat one unit at a time. Time your religious and policy changes - We mentioned this in our Religious Victory guide, but it’s worth stating here again. Waiting for the right time before striking, such as the implementation of the Wars of Religion Policy or Crusade Enhancer belief, which can drastically alter the outcome of battles. Build defensively around chokepoints, and avoid them when attacking - This ties into our point about patience; you want your enemy to be forced to trickle in whenever possible, and ideally over movement-slowing or stat-lowering terrain like Hills or Marshes, too. Keep great people to hand - Great Generals in particular of course, although others, when timed correctly, can grant access to the right Tech, Policy, unit or belief at just the right time when activated. Don’t feel rushed to expend them, and keep them alive at all costs! Don’t worry about diplomatic penalties when online - An obvious one to the more experienced players, but when in a multiplayer game of Civ, there’s no need to stress about diplomatic penalties like warmongering, because you are, essentially, in a permanent state of cold war anyway, simply because you never know when a surprise attack might come. Keep the unit training constant - Something we’ve learned the hard way is that, when in a long-term war, failing to continue churning out the military units can be costly, even if you feel yours can fend for themselves against greater numbers. Eventually, the AI or human oppenent your facing will win out in the war of attrition. Aim to get a very large army before attacking, and keep it permanently reinforced as you do so. Momentum is key, as losing it, and getting into that attritional war, is very costly both in terms of financial upkeep, and the opportunity cost of what your empire could be producing instead.
