If you want to test out fleet ideas against the AI (at 1200 point value), select "BATTLE" on the main menu, select Skirmish 1v1 on the left (right side is ranked), create a custom classic fleet and name it to save it, choose your skills, then just click Launch, and since you did not invite a player, it will pop up a screen where you will choose the AI faction you want to fight and whether it gets more or less points than you.

Note - I could not figure out how to do a 2v2 Skirmish against the AI, nor did I see how to adjust the point value to play with other point values than 1200 such as 1500 or 1650. Please comment if you know how and I will update.


IMPORTANT NOTE! concerning the Natural Selection achievement that I will place here:

This achievement may still be bugged, but even if it isn't, it really isn't worth it. My understanding is that you have to have a max level ship of each tonnage for each faction, Imperial Navy, Space Marines and Adeptus Mechanicus, as well as the special ship you get towards the end of the campaign. Trying to level up ship you otherwise would not use and then keep them alive throughout the campaign is a pain in the tush and really isn't worth it. If you follow my guide your campaign should hopefully be relatively stress-free, but it won't be if you try to go for this achievement as well.
There are better uses of your time. Just a heads up.



SAVE EVERY TURN! If my guide fails to prepare you for something and you mess up and lose the campaign, just back up enough turns and try again after figuring out what went wrong and learning from your mistakes.

Order of Sectors you unlock during the Imperium Campaign:

Cadia > Nemesis Tessera > Agripinaa > Chin-Chare > Belis Corona > Medusa > Scarus > Belial IV > Caliban & Scelus > Sentinel Worlds > Eidolon


TERMS:
Imperium = IMP
Adeptus Mechanicus = Admech
Space Marine = SM

Escort
LC - Light Cruiser
C - Cruiser
BC - Battlecruiser
GC - Grand Cruiser
BS - Battleship

Fleet Capacity is the point capacity of a single fleet and maxes out at 1000 at Level 13.
Leadership is the point capacity for battle and maxes out at 1650 at Level 15 (same as Level 16).

At Level 1, you start with Fleet Capacity 400 and Leadership 600.

Every level adds 50 Fleet Capacity and 75 Leadership, until levels 13 and 15 respectively as noted above.


Note - I tend to write 1500 points or 1500 leadership interchangeably throughout the guide

After the first 3 training missions are done and you finally get full control, you should have 3 fleets, 1 Imp, 1 Admech, 1 SM. The first "Mission", which is really just a set of objectives, is to take control of 4 systems; Cadia, the system due west and north-west of Cadia, and 1 south of Cadia.

What I did to start was, I went South from my starting point conquering systems along the way, then back up north to conquer Cadia, at this point having 2 of 4 systems needed for the objective. Then I jumped over the system due west of Cadia to get the NW system (a highly profitable system you want to get fast, just like Cadia). Now I had 3 of 4. Then, I skipped the final objective system and proceeded to take control of the rest of the Cadian sector then I went back to capture that final system. Once I captured 4 of 4, the Urgency Meter reset and the mission "Rise of Cadia" became available. Do not do this mission yet.

I did it this way because:
(1) I wanted to take the 3 systems I did take first before the enemy fleets in those systems reinforced themselves and made the battles more difficult. I could have gone east first and then come back I suppose.
(2) I wanted to make sure I captured all of the Cadian Sector before completing that "Mission" and starting the next step, why will become apparent shortly.
(3) Each turn that passed added another tick to the Urgency Meter. Every time a "Mission" is completed, whether an actual Mission or an list of objectives "mission", the Urgency Meter resets. Saving Missions to complete while letting the Urgency Meter rise can give you the chance to regroup, collect resources, and farm enemy invasions until you are ready to move forward. I could have waited longer to complete this first mission and milk the extra resources and farm invasions, but I doubt it would be necessary, you'll see why shortly.

Rise of Cadia Mission Available

STOP. You have captured every system in the Cadian Sector. You should have leveled up and now have the ability to recruit 1 new Imp fleet. MAKE SURE YOU RECRUIT THIS NEW FLEET BEFORE BEATING "RISE OF CADIA" MISSION! YOU WILL GET A FREE IMP FLEET ONCE YOU BEAT RISE OF CADIA. You do not have to recruit the new fleet immediately, just as long as you do before the mission. See my section on Technical Skills and Admiral Upgrades; monitor the admiral recruitment pool and recruit when you see an admiral with the abilities you like.

You are now going to let the Urgency Meter rise while you build up every system in the Cadian Sector to Level 3. Completely ignore Agri Worlds for now, first upgrade FORGE WORLDS (they give the most income), then HIVE WORLDS (next best income), then Shipyards. You also definitely want to upgrade the Listening Post system to start getting lots of Battle Plans. Ideally you were already trying to upgrade systems while securing the Cadian Sector, balanced alongside recruiting the ships you needed to win the battles. Once all the good systems have been upgraded to Level 3, and your fleets are how you want them and you have plenty of resources to spare, you *could* upgrade the Agri and Penal Worlds to Level 2 so they are ready to upgrade to Level 3 once you are flooded with income, but at the start of the game the 150+ resources you spend on upgrading them to Level 3 needs to be saved for your fleets and upgrading systems in Agripinaa (upgrading Agri worlds this early caused me unnecessary stress shortly after, not worth it).

You can let the Urgency Meter rise until it is into the final tier (past I think Tier 4 or 5, with Tier 5 or 6 being the "You Automatically Lose" point). Basically you can let the meter get close to the auto-lose meter level but obviously do Rise of Cadia before you auto-lose (and make sure you recruited that fleet first). You may be invaded once or twice, super easy and laid back to defend against though. Before doing Rise of Cadia you should have every important system leveled to Level 3, you should have 2/2 Imp Fleets, 1 Admech and 1 SM fleet. And you should be making some sweet income.

FINALLY - Do "Rise of Cadia"
You will be rewarded with another Imp fleet for free. So now you should have 3/2 Imp fleets, 1 Admech, 1 SM.

Next you will be sent to retake the Nemesis Tessera Sector. Capture the sector before doing the mission.

Next you will take Agripinaa. Again, secure the whole sector as fast as possible before doing mission.

Next Chin-chare. Also here note, if you plan to go east with Spire before Chinchare, still a good idea to move Spire to the location for a mission to make it available before going east.


IMPORANT NOTE: Arilla Bay in Agripinaa will need a fleet stationed in it to prevent Imperium Pirates from spawning. As will Jubal in Chin-chare to prevent Eldar spawning. There are a couple more in other sectors, just pay attention to sector and system text. But these are the early ones in sectors you need to hold and you will need to plan around.


It has been awhile so I forget what causes the Tyrannids to spawn, but that is a pivotal event in the campaign that can cause you to lose, so I will cover that in the next section.

The basic point of this section is to try to secure and build up each sector before completing the mission that resets the urgency meter and opens up another area. Also, review my Fleet Composition guide and be building toward having the ideal fleet and armada compositions complete and positioned in preparation for the Tyranid invasion.

I forget what the trigger for the Tyranid Invasion is, so save your game every turn so that if you accidentally start it before you are ready you can reload a previous save.


EDIT with gratitude to gaugephoenix who posted the trigger in the comments:

"After removing slaver threats in Agripinaa, a story mission show up in Belis corona sector in which you will first fight chaos then waves of tyranids come in. Finishing this mission triggers the tyranid invasion."


Once you trigger the Tyrannid Invasion, you will see that at least one system you own in each sector will be targeted by a Tyranid Invasion, and YOU CANNOT CANCEL OR DELAY THEM WITH BATTLEPLANS!

You must fight or let the Tyrannids auto-capture the system, you cannot delay or cancel them.

So you need to have Armadas of 2 Fleets with effective ship compositions like I advise in my "Fleet & Armada Composition" section spread out and ready to get to these systems and await the invasions, and then fight and win them.

Spire's armada can assist with this, but you will want Spire's armada to be able to break away and further the mission chain to the point you can end the Tyrannid threat, so keep that in mind.

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IMPORTANT! After fighting off a bunch of these invasions and possibly after a mission or two to further the story, but before you reach the ultimate Tyrannid mission, there will be another undelayable invasion wave/mission that will tell you to defend a system in each of I believe 4 sectors. The mission dialogues leading up to this may hint at the ultimate result/reward, but I want to emphasize what this means.

If you successfully defend these 4 systems, you will be rewarded with an additional 1 Imp, 1 Admech and 1 SM fleet. Like I emphasized in the Cadia section, make sure you already have the maximum number of each faction fleet, because these 3 new fleets will be added on top, so if you had 3/3 Imp fleets, you will now have 4/3. Basically you are getting fleets sooner than your Renown Level allows. If you fail, I believe you don't get the fleets.

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Eventually you will unlock the mission to end the Tyrannid threat. The mission to destroy the Hivemind Ship will be in the southeast-most system in the Belis Corona sector (where you start if you play as Tyranids), I believe the system is invisible until the mission step reveals it.

I recommend Spire having the Vengeance GC composition I recommend for him in the "Fleet & Armada Composition" section. The Hive Ship launches a psychic wave attack within a radius around it that you do not want your ships to be in, so you want ships that can dish out a lot of damage and from as far away as possible.

And while you could let the Urgency Meter rise as you farm Tyrannid Invasion, I do not recommend it, I recommend ending the Tyrannid threat ASAP, because the Tyrannid Invasions continue to be unstoppable and undelayable, and as the Urgency Meter rises, other factions are going to start invading and you could quickly get overwhelmed if you are not careful.

Upon destroying the Hive Ship and finishing defending against any leftover incoming Tyrannid Invasions, if you followed my advice in the Cadia section and then followed that same strategy as you captured sectors Agripinaa and Chin-chare and so on, namely letting the Urgency Meter rise as you collect income, build up systems, and collect even more income before completing the next mission; and if you followed my "Fleet & Armada Composition" advice and created the ideal 2 fleet armadas and mastered fighting battles with them; then the rest of this campaign should be easy.

You should be swimming in income and battle plans, have enough armadas to respond in time to any random invasion, and so have Spire move on to conquer the next Sectors and win the next missions that become available.

Same as the Tyrannids, different missions will proceed until they reach a finale where you can end the various faction threats that cause invasions; the Orks, Aeldari and Necron threats can be permanently ceased, leaving only Chaos (and the Imperial Pirates or Dark Eldar that spawn from not having a fleet in their system).

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When you get the chance to "follow" Inquisitor Darkhammer or not, I always choose not to, the battle takes place in the same system either way, and reward is effectively the same, and he is a prick.

When you get the chance to help or not interfere on behalf of a Fallen Space Marine; if you help him then he will show up in a mission as an AI reinforcement, but if you do not interfere, you will get a free Space Marine fleet as a reward (again, make sure you have the maximum # of Space Marine fleets already so you get this as a +1, so if you have 4/4 SM fleet, you would then have 5/4).

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Scarus > Belial IV > Caliban & Scelus > Sentinel Worlds

^ All of those sectors can honestly be abandoned after you have done their respective missions I believe, if you get tired of responding to random invasions. Although as you end faction threats, the number of random invasions should significantly diminish.



But basically, just follow the missions until you get to Eidolon and the final mission, beat it and win the campaign.

SPIRE's MISSION ARMADA

You have to use Admiral Spire to complete missions. My end game for his Armada is 2 fleets composed of Vengeance Grand Cruisers, at least 3 Vengeance GC in each fleet in order to be able to bring 6 Vengeance GC's once I reach Level 13 and am able to bring 1500 points into battle. Each fleet could have 4 Vengeance GC in them, however, the cheapest Imp Escort is the Cobra at 34 points, 4 Vengeance + 1 Cobra = 1002 points, it will not fit. However, you can have 3 Vengeance + 1 Exorcist in each 1000 point fleet, and the Exorcist's fighters allows you to scout so you do not need an escort. At 1500 points, if you are fighting a battle where you do not need scouts, bring 6 Vengeance; if you are fighting a battle where you do need scouts (such as against Aeldari or Chaos), bring 5 Vengeance + 1 Exorcist. If you really like the Exorcist GC and want to bring 2 of them with 4 Vengeance, you could once you reach Level 14 and have 1575 points available (4 Vengeance + 2 Exorcist = 1504 points). The Exorcist has 4 launch bays but only has 4 Macro Batteries with 9000 range which sucks when the Vengeance has 13500 range Lances and 18000 range Plasma Macro Batteries, so the Exorcist will need to be in Lock-On Stance in order to be able to support the Vengeance. So I would personally only bring 1 Exorcist into battle then, just for the scouting and bomber support when needed.

2 Fleets of 3 Vengeance GC + 1 Exorcist GC is probably the ideal armada for Spire.

NOTE - Once you get the Macragge (Space Marine Super Battleship), which is 736 points, if you want to bring Spire and the Macragge and you have reached Level 15 (1650 Leadership), know this. Macragge + 3 Vengeance GC + 1 Strike Cruiser Mark III = 1650 points exactly. Another good reason to run Vengeance GC's for Spire.



Non-Spire IMP Fleet Compositions

The same set up as Spire would be great if you run another 2 Imp Fleets together, but you could also try an all Avenger GC spam armada, which allows 6 Avengers at 1200 points (when you could only have 4 Vengeance), 7 Avengers at 1400 points and 8 Avengers at 1650. Spire's setup allows you to do varying missions with varying requirements and still crush everything, but if follow the strategy I recommend of camping all your ships in a Nebula so the AI comes to you, Avenger spam could work very well as long as you put them in Lock-On Stance. I was worried that their short range of 9000 would be a hinderance, as Avengers are phenomenal in Reload Stance due to 8 Macros firing super fast, but I was worried the fire rate of Lock-On would dampen that too much, forcing the Avengers to move to the enemy to get close thereby defeating the best strategy of camping in a Nebula. However, I tested Avenger GC spam in a Custom Battle against Chaos AI, and only being able to bring 6 Avengers at 1200 points, they still shredded the AI Chaos Fleet while camping in a Nebula in Lock-On Stance. Very fun.

If you want to run an Imp fleet with an Admech fleet, Imp Dominators (188 points) + Admech Lunars (210 points). Admech Lunars are the cheapest Admech Cruisers and therefore 1 Admech Lunar + 1 Dominator = 398 points, which allows you to bring 5 cruisers at 1000 points, 6 at 1200 points, 7 at 1400 and 8 at 1650 (same idea as with SM Strike Cruiser Mark III). At 1200 points+ you could replace an Admech Lunar with an Admech Dictator for the fighter support for Scouting, because the spare 2 points from each of the 188 point Dominators gives 6 spare points at 1200 Leadership. If you went Tyrant's for your Admech Cruisers, you wouldn't be able to bring Dominators in the Imp fleet, and the whole idea is to run an all-Nova Cannon Armada.

Here would be a good time to discuss how even small point value differences can affect what ships you can bring in a fleet. At 1350 Leadership, if bringing an Imp + Admech armada, you could bring 3 Dominators, 3 Admech Lunars, and either 4 Admech Firestorm Escorts (156 points) or 1 Imp Gothic (154). And with either of these choices, you would not be able to swap out an Admech Lunar for an Admech Dictator for ability to bring fighters to scout. If you had an Imp Lunar in your Imp fleet instead of the Imp Gothic as your extra to the Dominators, you have to choose the Admech Firestorms because the Imp Lunar would bring you to 1354 points.


Space Marine Fleet Composition

If you want to run an SM fleet with an Admech fleet, Strike Cruiser Mark III's (188 points) + Admech Lunars (210 points). Admech Lunars are the cheapest Admech Cruisers and therefore 1 Admech Lunar + 1 SC Mark III = 398 points, which allows you to bring 5 cruisers at 1000 points, 6 at 1200 points, 7 at 1400 and 8 at 1650 (same idea as with Imp Dominator). At 1200 points+ you could replace an Admech Lunar with an Admech Dictator for the fighter support for Scouting, because the spare 2 points from each of the 188 point SC Mark III's gives 6 spare points at 1200 Leadership. If you went Tyrant's for your Admech Cruisers, you would not be able to bring SC Mark III's, you would have to bring SM Vanguard Light Cruisers which would be a significant loss of SM firepower and durability.

I do not recommend bring a Strike Cruiser Mark I for the fighter scouting suppot in your SM fleet. It is too costly at 224 points (you can have 5 SC Mark III's in 1 SM fleet at 1000 Fleet Capacity, but only 4 Strike Cruisers if one of them is the SC Mark I), and the SC Mark III's 1 Heavy Lance provides a surprisingly large boost in firepower over the SC Mark I and II while at a much lower cost. And even if you do a 2 SM fleet armada for all SM ships, I do not recommend the SC Mark II either. Boarding Torpedos + Torpedoes could be fun in certain situations, but I find that overwhelming firepower is the best strategy, and the loss of the Heavy Lance on the SC Mark I and II just hurts too much. When I first started my Hard Campaign I ran some SC Mark I's with my SC Mark III's, and I kept wondering why it was taking forever to kill things, when I remembered an all SC Mark III armada crushing enemy's in my Normal Campaign. Quickly realized it was the lack of the Heavy Lance.


Admech Fleet Composition

This is where I stopped months ago and basically abandoned this guide. I'll finish it up with this:

If you run my suggested [Two Imp Fleet Armada for Spire], see above, then what I suggest for SM and Admech is to follow my advice in the SM section above, "Strike Cruiser Mark III's (188 points) + Admech Lunars (210 points)".

Try to create as many of these 1 SM + 1 Admech armadas as you can, and then figure out remaining armadas with any leftover Imp, SM or Admech fleets.

If you end up having 2 Admech fleets for 1 Armada, I went all Lunar Cruisers so I could have 7 of them at 1500 points, leaving 30 points to spare. Could probably sub in a Dictator for one of the Lunars for scouting support using its fighters.


Summary:

If you fight well in battle and don't lose any ships, then you should not need any reinforcements from a 3rd fleet, so a 2 fleet armada should always be sufficient. Especially since you will renown fighting with only 2 fleets instead of 3, and since it is good practice to fight this way, since if the AI builds mines, you will only be able to bring 2 fleets anyway. Might as well get good and not rely on a 3rd fleet as a crutch.

Do what works best for you, just remember the goal is to make an individual fleet as effective as possible and then combine it with another effective fleet to make the most effective armada possible.

My Tyrannid guide discusses this strategy in-depth, I'll summarize it here:

This works for run-of-the-mill Cruiser Clash battles. Many missions will require you to move around the map or attack the AI, so be prepared to adapt, but if you want to just curbstomp regular cruiser clash battles as you capture and defend systems, the following is easy mode.

Make sure you select Cruiser Clash as your exclusive battle type before you start your campaign for this strategy.

Even if you put your ships in a Nebula, the AI knows where you are and will come to you. We will use this to our advantage. Let's use my recommended Armada Composition for Spire as our example:


Make sure that each Fleet Admiral has the skill that makes invulnerable/quickly regenerates their flagship shield.

Park your Vengeance Grand Cruisers in a Nebula, and click the order that causes them not to move even if you order them to attack a target, "reverse thrusters" I think. Figure out where the enemy AI will be coming from, and have your ships arranged such that their broadsides face the enemy (Vengeance do not have prow weapons). Click on your ships and see a circle around them, if 2 ships circle's interlap then they will hit each other if they try to turn. Make sure your ships are in the nebula and that they are spread out just enough that if they need to turn in a complete circle they can without hitting another ship. Put your flagships with the shield skill in front of the regular ships that do not have the skill, still in the nebula.

How it should play out: The enemy cannot shoot your ships in the Nebula until they can detect them, so the enemy has to get close, and you will be able to shoot them as they approach before they can shoot you. The AI will often send escorts or other ships to detect you so that their longer range capital ships can shoot you from range; if you destroy all the ships near you that are detecting you, after a few moments your ships will be re-hidden by the Nebula, which will force the big bad battleship that was pounding your ships from max range to have to now approach the Nebula to detect your fleet, all while your ships get to shoot it. If your flagships are in front of your other ships, then they will tank the enemy's fire, and once their shields get low/drop, click the shield skill and watch it regen back up to full so your flagship can keep tanking fire while all your ships destroy the enemy one by one.


Beware of the environmental effect/malus (I think it is lightning storms or something like it) that causes damage in Nebulae, it causes tons of damage to ships in Nebulae and the above strategy will not work in battles with this effect active.


Alternatively, if you use my SM + Admech Armada composition with the Strike Cruiser MkIIIs and Lunars, since they have forward-facing Heavy Lances, you would do everything above, have them in a Nebula, make they they don't move when issuing an attack command, have your shield skill ship in front to tank fire, but you would select the "Fire-Forward" as opposed to "Broadside" option, and choose "Lock-On" Stance to extend their range, so that they all blast enemies with their Heavy Lances. You can always then switch to broadside or have them start moving and circling the enemy as needed.