Please don't let it be war of the five king it is so overuse. Maybe a period when dragon still roam the sky will be a better match because atlease westeros dragon can resist gunpowder weapon and melt solid stone.

My, you did a freaking good job in this first chapter ! The lore is here with some adjustement , your presentation of your character is just magnificent and i can't wait to see where you are going with this.
I presume Karl is going to meet with the Best familia of wolves in westeros
Pretty sure Ned and Karl are going to be BFF before you can say "White Walker" or "Hérésie"

Err, I would go with King's Landing. After all, it is an appropriate name when something of royalty lands there.

Please update soon.