Civilization V: The Swedish Saga, part 2 (430 A.D. to 1702 A.D.)
The Alliance fractures
1640 A.D.: A new wave of missionaries brings about the Second Awesome Awakening in Vienna, returning it to a majority-Awesomenist city.
To the East, Denmark declares war on Germany, led by a Great General.
1650 A.D.: Salzburg, an originally Austrian city held by Germany for centuries, is captured by the Danes. Germany is once again reduced to its capital of Hamburg.
1655 A.D.: The Danes drop out of the Continental Alliance, citing Austria's grievances with Sweden.
Not. Good. The Danes have a pretty strong military right now, and if they allied with Austria against me, I would be at war with two of the three civs directly bordering me.