With My Allies Filling the Court, Why Is Father Plotting a Rebellion?

After transmigrating into the body of a prince, Xia Kun, the ultimate slacker, wants nothing more than to stay out of things, live lazily, arrange flowers, admire jade, and explore secluded peaks. But circumstances force his hand: the princes scheme against one another, sharpening their knives and closing in on him. Japanese pirates are harassing the coast, the Xiongnu are invading the borders, and a Goguryeo army is massing at the frontier... Fine, this slacker will play along. When I finally rise, every one of you here will be a dead fish!