I was busy smashing the Korath to pieces, killing all of his ships, and got him down to his last planet, invaded, and had something odd happen. I got particularly unlucky with the odds thing, and ended up going down to 1 of my invading troops to zero remaining defenders. When I exited the invasion screen, the planet was still Korath, with 20 million population.

The next turn, the Korath military rating climbed very high, despite the fact that I outnumbered and out-teched the Korath.

It didn't cause me any trouble, as he didn't really have a military left, it was just weird. I was briefly worried that the Dread Lords had given him some ships, but fortunately that was not the case.