As soon as the gate opens and soldiers begin pouring out, press 1 to draw your sword. A small group of basic enemies will attack from the left. Take them out by interchanging left mouse clicks for swift attacks and right mouse clicks for heavy attacks.
Once this raid party has been dispatched, King Foltest will call out a group of enemies holding the high ground. They are pent up behind a barrier, which Foltest asks you to destroy using another ballista. Proceed down the wall until you see a prompt to jump down. Once in the courtyard, you’ll be attacked by another small group of soldiers. As the opposition here is relatively thin, it’s recommended that you experiment some with your magic abilities during these small battles. When the enemies are safely dispatched, carefully ascend the stairs. This bit is a little trickier. Three swordsmen and three crossbowmen await you at the top of the staircase. Take them out with carefully timed strikes. Success in The Witcher 2’s combat relies heavily on timing and observation, so use this larger skirmish as an opportunity to observe enemy tells. By figuring out exactly when an enemy will strike, you can parry or dodge that much easier.
Another group of six enemies will appear as you near the ballista, shielded soldiers and a two-handed swordsman among them. Take the weaker enemies out first. Carefully pick and choose your attacks and you should be able to kill them easily enough. After the weaker enemies are dead, attack the two-handed swordsman. His broad, sweeping attacks cover a lot of ground but are easy to see coming. Remember to use magic frequently to quickly wear him down. After bringing him down, only the shielded enemies will remain. Roll behind them and use quick attacks to whittle their health away.
Start cocking the ballista only to be interrupted by two more soldiers, one normal and one shielded. Compared to the last battle, this should be a piece of cake. Dispatch them quickly and go back to the ballista again to aim it. Three more soldiers will interrupt you, but can be easily dealt with using the same strategy as before. Finally, approach the ballista one last time to fire it.
Tucked away in the upper right hand corner of the map, behind the ballista and sandwiched behind a small house, is a strangely familiar dead Assassin lying amongst bales of hay. Examining him will grant you the Assassin ability, giving you a +25% damage bonus to attacks dealt from behind. This is especially helpful when dealing with shielded soldiers, or when sneaking, so be sure to grab it before you leave.
Upon firing the ballista, you’ll meet Aryan La Valette. He’s at the top of one of the towers and leading a group of enemy forces in an attempt to kill Foltest. Level up before heading up the tower. The best investment of your skill point at the moment is arguably the throwing dagger, as it will be needed for a quest later on and there’s no guarantee that you’ll be able to level up again before the quest presents itself. After leveling up, head over the bridge and engage another small band of enemies.
From here, head right and run up the ramps to find Aryan. You will be presented with three choices in the following conversation; you can attempt to persuade Aryan to give himself up, duel Aryan, or fight Aryan along with all of his soldiers. Of these, the third is clearly the worst option. Choose to persuade Aryan away from violence and the long term benefits will be the greatest, as you will eventually receive a +50 capacity upgrade when you encounter him again.