The year is 1066.
Since returning home to claim your throne in Norway, you've spent the last 19 years squabbling the armies and good will of your vassals in unsuccessful campaigns against the Danes. Now at age 51, encouraged by Harold Godwinson's own brother Tostig, you seek to cement your legacy as Harold the Conquerer of England... or die trying.
Before You Unpause
Send your invading army north to the Scottish county of Lothian. From there, Godwinson will not consider you a threat and will instead attack William the Bastard's invading army. Reliving the Battle of Stamford Bridge would not necessarily be suicide.
In fact, Hardrada often wins it despite his lesser numbers because of his high martial skill and good defensive position in York. But regardless of the outcome your army will suffer serious casualties, leaving you unable to fight off William the Bastard's invading army of 10,000 men. Your eldest daughter Ingregerd is unmarried. I suggest marrying her to Svend, King of Denmark as he will immediately be able to contribute something like 3,000 troops to your cause. Your second wife Thora, is well past her prime child bearing years at age 49 and offers you no adventageous alliances. I usually assign her as my spy master (most of the time your current spy master will be leading troops and will be unavailable to assign any jobs) and dispatch her to Middlesex to keep an eye on the English and Norman troops. And if she happens to be discovered or assassinated... oh well. You will want to select an ambition as well. I usually choose to start a plot to assassinate my wife Thora . This may seem cold hearted, but you are over 50 years old and have only two male heirs who usually don't survive very long given that they're both leading invading armies and they both want to secure their place as your heir. If killing your wife isn't your style, you could choose to revoke Vestfold, which will allow you to raise more troops and collect more taxes, or you could select Become Exalted Among Men. Most members of your council will be unavailable to assign jobs since they're currently leading troops with you. So I usually like to invite characters to my court to assign important council jobs to.
Typically, you can find a few claimants to either the Irish duchy of Munster or the French duchy of Britanny who are willing to accept your invite. Offer vassalization to Duke Isleifur of Iceland. He is your de jure vassal and will most likely accept. It will help to be able to raise his additional troops and later tax him. Increase your Crown Authority to Low. This will allow you to raise larger levies and revoke titles. Begin to upgrade your holdings in Trondelag. I usually prefer to build castle towns in both of my castles there for the additional income. I do not suggest upgrading your holdings in Faereyar as this only has room for one additonal building and you will not want to keep it long term.
Once You Unpause
Wait for your army to arrive in Thorian. During this time, Svend should accept your marriage proprosal, characters should accept your invitation to court and if you chose a plot to assassinate someone or revoke a county, characters should respond to those invites as well. Once your army is waiting in Thorian, the spymaster you stationed in Middlesex should be able to keep watch for when William the Bastard arrives. Wait until William's army arrives and is engaged by Godwinson's army.
Once they engage each other, move your army in to Northumberland to begin sieging English holdings. If you do not initially retreat all the way to Thorian or you do not wait until the English and Norman armies actually engage, there is a good chance that Godwinson's army will pursue you north, even in to Scotland and cause heavy casualties to your army. Once you begin sieging English holdings, invite your allies you join you. If you invite Svend of Denmark to join your war before this, he often sends his troops directly to Middlesex where they will be slaughtered by the English or Norman. If you wait until you are sieging English holdings, he will most likely send his troops to reinforce yours. Appoint your new Irish and Breton court members to council positions and assign them important tasks. I usually like to assign my Chancelor to fabricate claims on Bergenshus, which assuming I raised my Crown Authority to Low, will allow me to revoke the title without penalty with with a 5% chance of rebellion. This will allow m to raise more levies and garner more tax.
Assign a new Marshal as well, most of the time there's a far superior option than Tostig and the added martial ability will be helpful in your invasion. I also like to appoint a Court Chaplain who is not currently leading troops so that they can begin to convert my Norse counties to Catholic. This will grant you piety and reduce their revolt risk. Once you reach 100 piety, request a divorce. Once a diforce is granted, your wife dies or is assassinated, go to the character search and look for a new one. Select "Search All" and look for all un-married, Christian women.
Above all else, your goal should be to look for somoene to give you more male heirs. Prioritize young women with trais such as Hedonistic, Lustful or Midas Touched , which grant significant bonuses to fertility. Selecting a spouse with the genius or strong trait will also be helpful, as will selecting a spouse with high diplomacy skill. You will needs a lot of diplomacy to hold together your large demense, should you conquer England. Siege every holding of every county, progressively moving your army south.
Your spy master in Middlesex should observe the English and Norman armies grinding each other down. The bloodier and harder fought the battles, the better. After their initial two or three skirmishes, Williams army will most likely be down to 8,000 or so men. While you siege every holding in northern England, Godwinson will continue to draw his levies and send them south to fight William, continuing to grind down his forces to something between 3,000 and 6,000 men.
Do not engage either army, let them fight inflict massive casualties on eachother. Once Your War Score Reaches 100 DO NOT ACCEPT PEACE. The hardest part about playing as Hardrada is not winning the war for England, but keeping your claim on England. The more disgruntled Saxon leaders you have as vassals, the harder it will be to keep the peace. You no longer need to siege every holding of every county, that was more of a stall tactic that allowed you to garner additional revenue and later you will be given 25 piety for every church you hand out. If you simply siege the primary holding in each county, you will be granted that entire county and it's holdings once you accept peace and you will be able to assign vassals of your choosing to govern them. At this point, I would seriously consider sending Hardrada home. The moment he dies, you will lose your claim on the Kingdom of England and the war will be over. Even with the loss of his few hundred troops and his martial ability, your army sould be superior to that of the English or Normanst.
If, however, the English or Norman army's numbers remain above 5,000, you may want to consider engaging them with Hardrada and then sending him home afterwards. Hardrada's great martial skill is a huge advantage in any large scale engagement. Most often, Godwinson's armies and continually raised levies will eventually wear down William to the point that he surrenders and gives up his claim on England. Once this happens, he will turn his attention to you and begin sieging English holdings you control. If William wins his claim on England, he will not be your opponent and will take a similar tactic.
Continue to methodically siege the primary holdings of every English county but one, while simultaneously preventing the opposing force from retaking any of the English holdings you have already sieged. This usually involves watching the progress of your siege compared to the progress of your enemie's siege and judging whether or not you'll have enough time to take the next holding with enough time left over to then travel to the enemy army and prevent them from taking your holding. Ideally, with the help of the Danes and if need be some mercenaries, you will be able to take the primary holding in every English county before accepting peace. If, however, your army becomes outnumbered, Godwinson or William the Bastard call in a powerful ally such as France or the Holy Roman Empire or Hardrada becomes incapable or sick, you may want to declare peace before this. Remember, if Hardrada dies, you lose your claim on England, the war ends and you just lost thousands of troops for nothing. Once you've conqured as many English lands as possible and accepted peace, the hard part begins.
Stay tuned for Securing Hadrada's Claim on England: Part Two, which will advise you on how to delegate power in conquered land and how to avoid a sucession crisis.