This guide will tell you how to cancel both William the Bastard and Harald Hardhead, thus avoiding getting curbstomped hard as Harold of England.
The most important necessity of keeping yourself alive is alliances.
Don’t waste a second. Marry off your children to whoever has the most biggest alliance power. (I allied France, the HRE, and Croatia)
Call them into the wars 2 seconds after the alliances are formed.
Obviously, raise your levies. Along with that, hire the most biggest mercenary group you can buy. If you get into debt, I got an easy solution. Simply don’t care.
Once you done all that, merge the armies.
The War Plans
Try to peace out the literal bastard first.
William’s armies are most likely divided. When your allies’ armies are close to arrival, send your 7k stack over to whatever is the smallest stack first to take them out. If the other armies aid it in time, it won’t matter because most likely your allies will arrive in time too. From there William most likely won’t succeed. You might be able to white peace really soon but if you want to you could try enforcing demands, thus neutralizing Normandy longer.
After that, most likely all your allies made it onto the island. From there, send your stack over to Harald’s stacks in Northumbria. Once the stacks are retreating into Scotland, spare no time and go sack Nioaross. I was able to imprison Harald, getting a 100% warscore.
You did it! Congratulations you successfully cancelled William and Harald.