The Danes halt the advance
1903 A.D.: The Celts make a declaration of friendship with the Russians, still staunch allies of Greece. The UNK just doesn't really know what's going on anymore.
I'm starting to run out of bars on my "WUT"-o-meter. So there's some kind of dispute going on between Celtica and England, from what I can tell. And Russia hates everyone that's not Greece--England included. So... I guess... that's why? Maybe?
1905 A.D.: The Eiffel Tower is completed in Sigtuna. Everyone is just super psyched.
I get a gigantic happiness bonus from this wonder, which is something I really needed. Capturing all of these Danish cities is putting my happiness down the toilet, and we only just got indoor plumbing to make that metaphor relevant.
Danish forces from Aarhus and Copenhagen meet the UNK army outside of Viborg. They are spotted quickly enough that most of the UNK forces are able to fall back safely from the city.
The Danes have Norwegian Ski Infantry now, a unit of equivalent tech to my Caroleans. In terms of firepower, they are evenly matched. Since they heal every turn, the Caroleans are more resilient, but ski infantry have the mobility advantage in snow and hills. And Viborg is practically surrounded by hills. I elect to pull my front line back and let my artillery and gatling guns deal with them from a safe distance.
1907 A.D.: The Battle of Viborg rages on, with heavy casualties being inflicted on the UNK 1st Artillery. They are forced to abandon their exposed position on Viborg Bay and fall back to Roskilde to replace damaged guns. The UNK infantry continues to hold the line at the border, as reinforcements from Stockholm and Sigtuna rush down the road to their aid.