I wondered the same on my last playthroughs and a lot on the last. Thankfully, this thread is here just when I finished blowing up Ygerna (again).
The Black Ring seems to be a massive army with vast resources which now had decades to build up. Even if it can take the blow the Dragon Knight gave it, it still must be crippling.
If normal people are around the range of level 1 to 10 (Richard of Aleroth is level tenish as are seasoned bandits and most of the footsoliders of the black ring) and elite captains and leaders level 20 to 30, the Black Ring has lost 100s of very able soliders + a massive amount of non-standard fighters in the low and high 20s.
Plus a lot of generals, specialists, fortresses, and one main-attack fleet. Plus a lot of demons and flyingbeasts (demons as well as corrupted-dragon-things).
Whatever plans Damian had for now, he can totally forget about them. This does not matter as he does have time. What are another 20 or so years to rebuild his army? But the point stands, the Dragon Knight caused some massive damage to Damian's Campaign (apart from screwing up his personal life due to killing Ygerna).
