The War of Three Banners
The fifth century is off to a pretty good start. My economy is doing great, but my Happiness is close to going negative. I start researching Physics so I can build the Norte Dame wonder, which will give me a big bonus to Happiness and Faith.
430 A.D.: The first mint is constructed in Stockholm, printing coins bearing the visage of the first High King of Sweden.
490 A.D.: Denmark requests a gift of luxury resources from Sweden. They happily accept, having much to spare.
I made a similar deal like this with Austria. It might seem like charity, but as you'll recall, I get Great Person points for every civ I declare friendship with, so I'm investing in keeping the Danes on good terms.
550 A.D.: The progressive Swedish government presses their monarch to sign the Book of Sovereignty. It puts into effect a system of collective rule, giving more power to Lord-Governors on the local level and taking power away from the High King. Rebels in favor of a strong monarch are quickly put down by the combined might of the lords of the West, the Vale, and the Storm. The short, one-sided conflict comes to be known as the War of Three Banners.
This policy gives me a free settler, and lets me train settlers faster. It also completes the Liberty policy tree, which grants me a free Great Person. I choose a Great Scientist.
And no, Civ doesn't have a rebellion mechanic. But it adds flavor to the narrative to imply struggles within my borders, so I've given myself permission to do so.
565 A.D.: A Swedish Great Scientist founds the Academy of Stockholm.
Great Scientists can be expended for a one-time, huge boost to Science, or they can build an Academy that gives you ongoing Science. The latter is clearly the better long-term option, especially this early in the game.