About 25 turns into my first Denmark campaign, managed to wreck the whole Kalmar thing by killing all of Norway's family members in a battle outside Akershus, but otherwise doing well for myself.

Also, I'm thinking that Denmark isn't exactly set up for war with the HRE, since they give you one of, maybe THE single most defensible border in all of Total War with the two crossings just outside Hamburg. Your turf in Livonia, not so much.