Since i was asked about this recently, and no one else has taken the time to explain how the camp destruction works, I thought I would take a stab at it.
This description was derivied from empirical data I gathered in actual battles and many iterations of Asipak's Sim.
The destruction of a camp is the additional amount of time needed to destroy a camp after you have defeated the enemy that occupied it. It is in addition to the actual battle where you defeated the camp, and is represented by the 'Health Bar' that appears when the inital
winning battle is over. The amount of time needed to destroy the camp is calculated the same way as the Battle itself: 20 seconds per round (10 seconds for fast generals like Vet, Grim and BHG).
Side Note: This addtional camp destruction time is why it normally is better to have to Winning Advanced Block versus a losing one; Winning in 5 rounds will last just as long as losing in 7 rounds assuming you are not doing something silly like blocking with Cannons.
The number of Rounds it takes to destroy a camp is determined in much the same way as the battle was calculated and is dependent on the camp type and the unit type(s) originally sent to the battle.
The amount of damage a camp can sustain before destruction is as follows (derived emperically):
Code:
Building Damage
Bandit camp 250
Watchtower 1000
Reinforced T. 1500
Stone tower 2000
White castle 2000
Witch tower 2000
Bone church 2000
Dark castle 2000
Now comes the important part: The amount of damage you can inflict per round is entirely dependent on the unit types represented in the actual battle. They do not have to be alive at the end of the battle to help with the destruction of the building, they just had to be a part of the garrison assignment at the start of the battle. It also does not matter how many are included to represent; as far as the building destruction is concerned, sending 1 cannon is the same as sending 100. You'll see a few examples of this tactic used in some of my guides (mostly Roaring Bull), where I have a mix of unit types being required to take the towers down faster.
Lesson Guides
So as an example:
Suppose you win a battle using your Vet general against some camp, and you had sent 100R and 150K(Cannons). Each round, you would hit between 255 and 390 in damage based on the following Unit Types that are represented:
Recruit (15-30)
Cannon (120-240) * remember cannons get double the effective damage against buildings
General (120)
So in this case a regular Camp is only going to last 1 round and a Dark Castle or Witch Tower 6-7 rounds depending on your accuracy rolls.
Why is all this important?
If, in this same example you were to replace 3 of those recruits (or cannons) with a Militia, a Soldier and an Elite, suddenly you are hitting for 60-120 additonal damage each round on the building. Now that Witch Tower will only last 4-5 Rounds.. you just shaved 20 seconds off your potential destruction time so that Advanced Block may work after all!
-Lesson