Crusader Kings III

What is the North Sea Empire and how can it be created?

When reading the achievement description, you might ask yourself: "WTF is the North Sea Empire, there is no such Empire on the de jure empire map?" The North Sea Empire is a special Empire that can only be formed by taking the major decision "Secure the High Kingdom of the North Sea", which requires you to fulfill some special conditions other than the usual control of a majority of its de jure counties. This major decision will show up in your decision list once you acquire either the kingdom title of Denmark, Norway or England without being feudal or already having another Empire title, so you can look up and track the requirements in game from that point. You must use this special decision to create it, do NOT try to create it by using the more general "create a new Empire" decision.

The requirements to form that Empire are:
- you must be independant and have fame level illustrious (3) or above
- you MUST NOT hold any other Empire title
- your culture MUST NOT have reached the high medieval area (shouldn't be a problem, since we need to stay tribal for the achievement anyway)
- you must personally hold all three de jure kingdom titles (Denmark, Norway, England) for at least 30 years. If you die and continue as your heir, that timer will be reset even if you do manage to arrange your heir to inherit all three kindoms. You only need to hold the titles, you don't need to hold the complete de jure territory of those kingdoms
- You must completely control an area called the North Sea Heartlands. You can click the name of that area in the requirements listed for that decision in game to have that region outlined for you.
If you want to know in advance, the area contains the following duchies: In Denmark, the duchies of Jylland, Sjaelland and Slesvig. In Norway, the duchies of Vihin, Egdalfylki, Gulapinslög and Praendalög. In England, the duchies of Kent, East Seaxe, East Anglia, Jorvik and the Eastern part of Mercia.

Once created, the North Sea Empire will contain the Kingdoms of Norway, England and Denmark as its de jure kingdoms (The rest of the British Isles will be a new potential "Empire of Alba" and the Scandinavian Empire's de jure territory will just be reduced to the rest of Scandinavia without Norway or Denmark). Creating this Empire will instantly make you feudal (regardless whether you fulfill the usual requirements to become feudal) and turn all of your tribal holdings into castles for free. It also gives your current ruler a massive bonus to all coastal levies, naval speed and embarkment costs, wich makes creating this Empire an ideal starting point on your journey to Viking World Domination - as well as a great starting point to play on and complete some others of the more difficult Norse achievements like "Blood Eagle" (Conquering all of the British Isles as a descendant of Ragnar Lothbrok) "Faster than the Fox" (Conquering the whole Kindom of Sicely before 1047), Miklargardariki (The one in which you need to conquer Thessaloniki as an Asatru character while holding an Empire that isn't Byzantium) and "Far from home" (Having your capital on an island in the Indian Ocean as an Asatru character, though that last one can certainly be done much faster in a seperate playthrough by using Varangian adventures to get there). Contrary to the partially wrong achievement descriptions in the x-box achievements, you don't need to be tribal for any of those follow up achievements (only for the Canute the Greater achievement), so you can do those despite being converted into feudal by forming the North Sea Empire. You also don't need to worry about staying Norse during the scripted Norse culture devide, you can be Danish, Norwegian or Swedish. Look up the in game achievement descriptions for the correct requirements.

Which starting character to pick?

I highly recommend to play as one of the three tribal sons of Ragnar Lothbrok from the "Wrath of the Northmen" scenario (not Hafdan, because he starts as feudal), so you can also get the "Blood Eagle" achievement. They are all part of the already quite well established Sidurdr dynastie and as your brothers they can easily be persuaded to become your allies without an additional marriage, which will help you getting started and expand in the early game.
If you don't care about or already have the blood eagle achievement, you can play as any existing or custom created tribal Norse Asatru in 867, but IMHO being one of the Sigurdrs still makes it easier than being a random custom created nobody with optimized ruler skills, but no easy starting alliances. Technically, you could probably even do this as any other tribal character with an unreformed pagan religion (I haven't verified whether outsider cultures can form the North Sea Empire, but at least the requirements don't say you need to be Asatru or North Germanic), but since about two third of the counties you have to conquer for this are Norse Asatru, playing as anything else would make it much harder.

Either of the three brothers has something going for him. Ivar the Boneless is the best Warrior King (Martial education) and starts with free additional special troops, but he starts in a rather unfavorable position on the British Isles surrounded by other cultures and religions. Björn Ironside is the oldest and least suitable character for the early game (diplomat, pretty bad other stats), but has a very easy starting position surrouded by other Norse petty kingdoms and chiefdoms that can easily be conquered. Sigurd Snake Eye is a mediocre character with the best starting position to form his first kingdom (Denmark) very fast, since you only need to conquer few other counties to do it, and then easily expand into Norway, but his position is also more endangered. He must expand and grow stronger quickly to not be overrun either by the powerful Christian Karling Kingdoms from the South or by the Swedish (though you can usually achieve an alliance with the latter).

Tips for getting there

- Efficient conquest:

Regardless which character you picked, you want to grow as fast as possible in the early game, so no matter whether you have a martial education or not, pick the authority lifestyle (which gives you +0.3 to control growth) and first unlock the perks "serve the crown" (another +0.3 to control growth) and "strict organisation" (bonus to increase control councillor task progress), so you can raise your control in newly conquered territory quickly to get more levies and to diminish the risk of rebellions. Also try to get a decent marshall ASAP.
If you play as Ivar or Björn, you start being at war with Northhumbria and/or East Anglia together with your brothers. Raise your armies and try to end that war quickly and decisively, possibly scoring a bit of land in the progress. If you play as Sigurd, you aren't involved in that war and shouldn't get involved, but start picking off your weakest Norse neighbour chiefs instead.

Once those initial historical wars are over, try to negotiate alliances with at least two of your three powerful brothers (if you aren't playing as Sigurd, you might not want him as an allie and instead pick him off early while he's still weak, because you'll eventually have to fight him for Denmark sooner or later. He shouldn't be your very first target though, there are easier ones and you don't want the powerful Karlings as neighbors quite so soon if you don't have to).

Now you should start to expand by conquering the weaker Norse chiefdoms and Petty Kingdoms in Scandinavia. Even if you play as Ivar, don't bother fighting the English or the Scottish Lords yet, because you will have constant trouble with religious and cultural rebell factions popping up if you start there. The Norse Asatru counties are much easier to integrate into your realm. Once you raised the control level after the initial conquest, they will be loyal and provide you more troops to go after the more difficult enemies and to keep your future foreign conquests in check. If you don't play as Sweden (Björn) yourself, you'll want to try conquer the four Norwegian duchies that you need for the North Sea Empire before Sweden gets them. That way, you won't have to fight Sweden and can keep them around as a powerful and reliable Asatru allie to help in your wars. Another possible approach is going for the Swedish lords early while they are still weak and prevent Sweden from rising to power, incorporating them into your own realm instead. Regardless which path you chose, go for the Norse Scandinavian counties early, because Sweden tends to get very powerful and spread over all of Scandinavia if left unchecked.

Save up some money to form your first kingdom (Norway or Denmark) as soon as possible, so your realm doesn't get fractured into independant Duchies if your character dies. Once you are a mighty king, some of the weaker remaining Norse chiefs and Petty Kings can be persuaded to become vassals by diplomatic means, which can be the quicker and smoother way to expand than conquering them all by force.

Once you have conquered enough Norse counties to become culture head of the Norse, switch the culture fascination to discover siege engines, because having those will make conquering the Anglo-Saxon Castles much less tedious.

Once you conquered most of Norse Scandinavia and Denmark, you will be powerful enough to conquer England. Likely none of the NPC lords in England will have succeeded in founding the Kingdom of England in the meantime, so the most you will face are some more powerful dukes. They shouldn't be any trouble at that point, unless they have formed powerful alliances. In that case, it can be helpful to first break up those marriage alliances by some assassination schemes, if your intrigue and/or your spymaster are good enough to pull that off.

I recommend to NOT conquer the county of Kent with the Christian holy site until you already fulfill all the other requirements for forming the North Sea Empire. Leaving that Catholic holy site in Catholic hands will greatly reduce the danger that the pope launches a grand crusade for the Kingdom of England (I made the mistake to conquer Kent and I had to defend against a crusade during the 30 years of waiting time. Defending England against pretty much all of Christian Europe coming for you at once with only Asatru allies at your side is quite the challenge).

-Holding the kingdoms for 30 years:

Holding all three kingdoms as one character for 30 years is probably the most difficult part of the achievement, because as tribal rulers we are stuck with confederate partition as sucession law and we can't form another Empire. When we first conquer all 3 kingdoms, our character will likely not be a spring chicken any more and probably won't survive for another 30 years, so we either need to have only one male legitimate offspring or we need to reconquer the two lost kingdoms from our brothers quickly and then survive for another 30 years. Note that getting the lost kingdoms back by murdering your brothers likely won't work, because Scandinavian NPC kings tend to introduce the Scandinavian elective law for their kingdoms, so your player heir likely won't inherit their brother's kingdoms even if they die without children. He will have to win them back by war (as a brother, you do have a claim on the kingdom title, so one succesful war per kingdom is enough). There are basically three possible ways to make this easier:

1) Sire only one legitimate son:
As soon as your wife has given birth to your first healthy son (hopefully not twin brothers), divorce her and marry a venerable old lady with good skills instead who is beyond her fertile years. Also have no concubines, because children of concubines are considered legitimate and are eligible as heirs. To avoid the risk of ending up without any player heir in case your one legitimate son should die when you are already too old to produce a replacement, seduce some unmarried young ladies and produce a few bastard children, so you can always legitimize one of those bastards if you need a replacement heir (the mothers should be unmarried at the time of birth, otherwise the child might be claimed by her spouse as theirs and just get the disputed heritage trait instead of the bastard trait when you try to claim they are yours, in which case you can't legitimize them to be your heir).

2) Be a horrible father ;-) :
Don't avoid having more children, but instead kill off all but the one most capable son when you reach old age.

You can't use the murder scheme against your own children unless your character has the trait "sadistic", but you can imprison and execute them without a reason (Make sure to first imprison all of them before you start executing, because once you executed one of their brothers, your remaining children will hate you and are much less likely to not resist arrest.) This will get you the negative trait kinslayer and will give you a lot of tyranny points (unless your sons happen to have comitted crimes that actually justify their execution), but as a highly famed king with the maximum long reign bonus, you will hopefully manage to prevent a rebellion.
As the head of your dynastie, you can also disinherit a son at the cost of dynasty fame instead of killing him, but that decision is pretty expensive in dynasty fame, so you won't be able to do that with too many children.
A sneaky way to dispose of superfluous heirs is having them serve as a knight under an inept commander in a small army with just a few levies, then send that small army to raid in a kingdom that has a big enough army to completely wipe out your small raiding army in a devastating defeat (don't have them command the army themselves, commanders have much better chances to escape alive from such a defeat than mere knights have). This tactic doesn't work very well with Norse Asatru characters though, since they have a few stacking prowess boni from culture, religion and holy sites and thus usually have absurdly high prowess values that give them a good chance to escape alive even if the army is otherwise fully wiped out

3) Accept the sucession war, set your player heir up for success and his brothers for faillure:
When you have a male player heir and your wife gets pregnant again, give your son some of your well secured and profitable counties to rule and make him a duke, even if he is still underage (because you can't give him land that he doesn't stand to inherit, so if you want him to have a strong personal domain, you have to give him land before he has multiple brothers that stand to inherit your lesser titles). Just don't give him vassals yet, because adult vassals are very likely to rebell against child lieges. Being a ruler early will give him a chance to earn aditional skill points and start accumulating fame and piety, he will also unlock lifestyle perks much more quickly as a landed ruler than as an unlanded character. Once he is adult, give him some more of your freshly conquered fiefdoms at the border of your realm that border weak neighbours, so he might conquer more land for himself on his own and earn fame in the process. If he is suitable for the job, give him a position in your council. Arrange a marriage for him that will give him a powerful marriage alliance. Also try to conquer some more land that isn't part of the de jure lands of your three kingdoms and give it to vassals (as long as those lands aren't enough to fulfill the creation requirements for another de jure kingdom, those additional vassals will stay vassals of your player heir, making his kingdom much stronger than those that get inherited by his younger brothers and become independant)

In contrast to that, don't give any land to your younger sons and marry them to wifes that won't give them alliances. Following that advice should usually ensure that your son is the preferred heir for your vassals and well established by the time of your death, so he won't have major problems with rebell factions and can soon declare war on his weaker brothers to reclaim the kingdoms.

Remember that your heir must stay alive for 30 years after inheriting and/or reconquering the three kingdoms, so maybe don't try to celebrate your 90th birthday as your current character, but start taking some risks and/or accumulating a lot of stress and traits that damage your health once your preparations are done and your heir is old enough and established to take over smoothly.

To stay alive for 30 years, take the usual precautions:
- don't command armies personally
- never let an enemy succesfully siege or raid your capital
- accumulate positive health traits to prolong your life expectancy and reduce the risk of illnesses. Some perks from the medicine skill tree are a great help for that, also accumulating experience as a hunter and/or traveller gives health bonusses (but of course, travels and hunts can also trigger risky events, so do that while you are young, then stop doing it when you reached the experience level). Also, employ a capable court physician.
- avoid high stress levels, make sure you get some character traits that help you reduce stress easily and without negative health consequences.
- to avoid getting murdered, make sure your spymaster, court physician and cup bearer always like you a lot. Pick people as your physician and cup bearer who have personality types that are described as unlikely to be agents (like paragons, empaths, honorable or compassionate characters, not e.g. "Rapacious villain" or "insane adventurer"). Same goes for body guards and food tasters, if you have the royal court expansion. Also, romance or seduce your wife, she might save you from a murder attempt if she is your lover or soulmate and might also help out in cases of mental breakdowns.

During those 30 years, you don't want to make too many powerful enemies, but that doesn't mean you have to sit quietly and twiddle your thumbs. Use that time to wage war on easy opponents and work towards other achievements, like e.g. conquering the rest of the British Isles or carving your way through pagan eastern Europe down towards the black sea to later conquer Thessaloniki once you create the North Sea empire. It is useful to conquer especially tribal holdings that you want to conquer before you create the North Sea Empire, because creating the empire will convert all of those to feudal for free, not just the ones within the North Sea Empire's de jure area. Just don't pick too powerful opponents, don't antagonize the pope too much and don't personally lead armies.

A few pitfalls to avoid:

Remember that you and your player heirs need to stay tribal and need to have an unreformed/not organized faith. Also, while you don't necessarily have to stay Norse, you mustn't have a culture that already reached the High medieval area. Thus make sure to avoid the following:
- giving your heir a castle holding as his first county (which could cause him to settle down and become feudal)
- giving your heir a county to rule whose population follows an organized religion or has a high medieval culture. He might convert to the regional culture or religion and thus make the achievement impossible when he takes over as your heir. Converting back or having that character die with another tribal pagan as their heir won't help, the achievement is blocked once your ruling player character was not tribal or not unreformed at any point during his rule!