Following the rules for the Campaign Systems - World Conquest - The Basics, the rules here are an expansion on the regular ones, adding in siege warfare to your arsenal of creating the perfect campaign.

I present to you the Campaign Systems - World Conquest - Siege Warfare Expansion

Siege Warfare Expansion Set

Instruction & Rules Manual

General Information

In this expansion, you will be able to use Siege Warfare to compliment your use of Land Warfare. This includes a new set of Siege Rules to help batter down the gates of enemy castles.

Changes

The following changes are made to the Defensive Actions "Long Term Defensive Actions" chart:

The following changes are added to the "Defensive Repair" chart:

Siege Battles

All Siege Battles are now fought using a full castle and the New Siege Rules which are below. The minimum army size requirement for Siege Battles is 2000+ points.

New Siege Rules

The Anatomy of a Castle

There are four basic parts to a castle:

The Walls & Ramparts

The Towers

The Gate

And The Courtyard

Walls

1 Section of wall is about 12 inches long. Troops on the walls count as being in hard cover so any missile troops suffer -2 to hit penalties for shooting at them as they hide behind the ramparts.

Troops must be placed in single file on the wall which will leave enough room for the attackers to be placed on the wall as well. Note that this rule is very important. You may place as many models as you wish on the walls as long as they're in single file and leave a 1" gap from the models to the battlements, any models assaulting the walls will be placed in this gap.

Musicians on walls never have an effect on the battle outcome. Troops on walls are always stubborn.

Towers

The strongest point of a castle, they make ideal positions for war machines. A single unit may garrison the inside of the tower. Units can move through it from the walls, but they cannot stay in there so long as there is a unit garrisoning the tower. Only one unit is allowed in a tower at a time.

A single war machine and its crew can also be placed on top of towers, though it is unable to move, simply pivot on the spot. This is the only unit that is in exception to the regular "Only one unit is allowed in a tower at a time."

Troops in towers can fire in any direction. Troops on top are vulnerable to missile fire, but are still counted as in hard cover. Troops inside towers fire through arrow slits and are thus protected from any form of harm, less the tower collapses. Towers are considered to be 2 levels and allow for 5 models to shoot per level. There is also the top level where up to 10 models can shoot from.

Musicians in towers always have an effect on the battle outcome. Troops inside or on top of a tower are always stubborn.

The Gate

The gate is the weakest point of a fortification as it's easier to break through that then a wall or tower.  At least two models are needed to open or close the fortress gates from the inside. This can be done in their movement phase and suffer no penalties for their movement. The gates obviously can't be opened from the outside.

Moving Through a Gate

All except larger models (I.E. Dragons, Giants, and other large monsters) can go through gates. There is no formation change needed, it is assumed units simply pour through and reform on the other side. It is not uncommon for a unit to be half on the inside and half on the outside of the gate, as long as the unit remains in contact with the gate piece to show this.

The Courtyard

The courtyard is the area on the inside of the castle which the walls and towers surround. This is usually open ground. Troops can move onto the walls and towers from the courtyard, explained later, freely, provided that the enemy doesn't hold it.

No troops in the courtyard are stubborn and fight normally.

Well-defended Wall

For all walls or towers being defended by any player in this game, the attacker will always receive a -1 To Hit modifier for being well defended. The models must count as defending the obstacle thus must be in base contact or on top of the structure in the correct position. You only receive this for walls and wall-like obstacles, not towers. Anyone behind a well-defended wall is also counted as being in Hard Cover.

Movement

Models defending a castle are organized into units just as they would be normally, but for a siege you will find that units between 5 and 12 models are the most convenient sizes (of course this isn't mandatory).

All troops, including besiegers, can adopt a skirmish formation when deployed on the ramparts or the towers to aid with movement.

Skirmish Formation

If you decide to deploy your troops as skirmishers, the models are placed up to 1" apart. Should the unit be split up as a result of casualties, the player must rectify this problem as usual.

Movement on the Walls and Ramparts

Follow the regular rules for movement when moving around the towers or walls. Remember there's only room for only one rank of troops on each wall section, so if the rampart is completely occupied, there will be no room for extra models. However, a unit may pass another unit during the movement phase as long as all the troops who are on the wall end the phase so that the wall doesn't have a second rank on it and all models are still in single file.

Troops can freely move from a castle tower or a wall section to any adjacent wall section or castle tower if they have enough movement left available to them. A unit cannot garrison a Tower if they have marched that turn.

March Moves

The Enemy Sighted! Rule only applies if you are in the courtyard, between the gate, or on the ground by another unit that is also in the courtyard, between the gate, or on the ground. Otherwise it doesn't affect the unit's ability to march on ramparts and towers.

Movement onto Ramparts or a Tower from the Courtyard

A unit may move from the courtyard to the ramparts or onto a tower during its movement phase if it can move into base contact with the wall or tower. It cannot move into the tower from the courtyard if it has marched that turn.

Models in the unit are placed anywhere within the tower or along the rampart that the player wishes. If there is insufficient room for all the models, the rest of the unit is left in the courtyard in base contact with the wall or tower and can be moved into it or on top of it as soon as a spot is available.

Cavalry Units, Monstrous Cavalry Units, Beasts, and Monsters cannot go onto the ramparts. Cavalry units, Monstrous Infantry units, Monstrous Cavalry Units, Beasts, and Monsters (and their riders) may enter towers but each model counts as three infantry sized models and a Monster (and rider if there is one) counts as 5. Obviously one must be reasonable in size. Only smaller monsters such as Griffons, Royal Pegasi, Hippogriffs, and other smaller sized monsters can enter a tower. Beastly monsters such as War Hydras and Dragons cannot.

Movement from the Walls and Towers into the Courtyard

Units may move from walls or a tower to the courtyard in a single movement phase and placed in any formation normally allowed. This movement costs half the unit's movement and cannot march if it's coming out of a tower. Measure the remainder of their movement from the base of the tower or wall to complete the movement phase and allow the unit to form up. If the unit cannot fully form up for whatever reason, the left over models remain in or on the tower or ramparts.