Siege Engines (TCG)

Note: This chapter refers to rules and concepts used in TSR'S BATTLESYSTEM™️ miniatures rules. Since siege warfare is, by its very nature, an activity involving scores, hundreds or even thousands of troops. BATTLESYSTEM™️ is the system of choice. Of course, this doesn't mean that small segments of a siege can't be roleplayed to great effect using standard AD&D® rules.
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==Siege Engines==
Siege engines break down into two main classes. These are bombardment engines which are designed to hurl large missiles, often with little or no accuracy, but doing a great deal of damage if they hit. This category also includes cannon and mortars, which might not be allowed in all campaigns. The other category, crushing engines, includes all non-missile devices designed to breach gates or walls through impact or other methods.
===Bombardment Engines===
All bombardment engines make use of the same concepts and terms. These are listed below:
AD is the size (and number) of attack dice rolled when the device is fired. Attacks can be rolled against specific target units or reasonably large building features; to be eligible as targets, building features must be at least 3" along one dimension.
Apart from the ballista (discussed below), no bombardment engine can fire at a single figure, whether that figure is a hero or part of a unit. Targets of artillery attacks are not allowed to make armor checks; every hit does damage.
A bombardment engine only inflicts half the actual hits it rolls (rounded up) when firing at a unit in skirmish formation. If 7 hits were indicated, for example, a skirmish unit would only suffer 4.
Hits is the number of hits required to disable the machine. "Disable" has different definitions, depending on the engine in question.
Range is given in minimum and maximum distances. There are no short, medium and long range categories for these weapons, and they don't receive a range bonus for elevation.
Crew is the number of figures required to operate the weapon at full effectiveness. The weapon can operate with less than a full crew, but its rate of fire is slowed to half speed. A weapon cannot fire or be loaded if its crew has been reduced to less than half the number given here.
Crew members can defend themselves against a melee attack, but they cannot fire missile weapons or make a melee attack. If they do either, they are considered not to be crewing the weapon during the turn in which the attack is made.
Rate of fire is the number of turns required for the weapon to be reloaded.
Move is the distance the weapon can travel in one turn over clear, flat terrain. A bombardment engine is treated as cavalry for purposes of determining what types of special terrain it can negotiate, and how quickly it can move through special terrain-half speed through light woods or when ascending a slope, and onethird speed through shallow water or brush/scrub.
A weapon can only be moved when it has a full crew. An artillery weapon cannot move and fire in the same turn, though it can be moved fully loaded, ready to fire the turn after it moves.
A turn in which a bombardment engine moves does not count for reloading or for purposes of determining rate of fire. Such a weapon can change facing during a turn when it is being reloaded.
Scatter is a concept common to all missile weapons. When a projectile misses its target, the concept of scatter determines exactly where the projectile does hit.
The odds that a given shot will scatter vary from weapon to weapon, and are given in the individual descriptions, as are the possible distances that shots might be off the mark. In all cases, however, the method for determining direction of scatter is the same.
If a shot scatters, roll 1d10 and consult the following chart:
For example, a heavy catapult shot at an enemy unit scatters. The 1d10 roll is 7, which means that the shot is long and slightly to the right. Checking the text following the table that describes this weapon, we find that the shot misses its mark by 1d3 inches.
If the shot is aimed at a vertical surface, the scatter diagram is still used to determine the impact point. A roll of 1, for example, indicates that the shot fell short of its mark. If this is the case, but the round still reached the target, then the point of impact was lower than intended. If a roll indicates that a scattered shot went high and the target is too low to be struck, then the missile will continue past the target and strike the ground beyond it. Thus, a shot fired at the top of a wall or flanking tower still has a chance of doing damage to the keep inside the walls even if it misses its mark.
Dungeon masters who are running an AD&D game campaign, not just a skirmish fought with the BATTLESYSTEM™️ rules, might consider adding the "artillerist" weapon proficiency:
Artillerist
Those with this skill are trained in the use of various siege engines. In addition to preventing the drawbacks of nonproficient weapon use, if a character with this skill commands the crew of a bombardment engine (i.e., is within 1" of the weapon when it fires), the chance of a shot scattering is halved. Warriors may specialize in this skill, but there is no change to the weapon's rate of fire for experience levels or specialization.
===Ballista===
Also referred to as a mangonel or scorpion, a ballista looks like a huge crossbow. It fires projectiles that look like oversized spears. Although not as effective as catapults or trebuchets, ballistae could inflict impressive damage against buildings (the projectiles aren't as heavy as trebuchet missiles, but their moment of inertia-and hence their "stopping power"-is very high).
Ballistae were used by the Romans, both as land weapons and as shipboard devices for firing grapples at enemy vessels to pull them alongside for boarding.
The potential energy stored in a bent and cocked ballista is considerable, making the loaded weapon somewhat fragile. As the old saying goes, "A bent bow is seven-eighths broken". If the ballista has suffered serious structural damage (that is, if it has been reduced to 2 hits), there is a 20% chance each time the weapon is reloaded that it will misfire, destroying the weapon. If a ballista misfires, it fires as soon as reloading is complete, whether or not the crew wants it to. The shot is very inaccurate, however: it automatically scatters, and the scatter distance is twice normal. Each figure within 1" of the device suffers 1d3-1 hits (no armor check) as the ballista shatters. Of course, the device is useless from then on.
A ballista shot has a 15% chance of scattering: scatter distance is 1d3", half that (rounded up) if the range is 13" or less.
A ballista with full crew can fire at a single large-sized individual figure (a dragon or the leader of a troop of giants, for example).
===Bombard===
Over the centuries, weaponsmiths developed a staggering variety of different gunpowder-fired devices-many of which were more dangerous to their crew than to their target. The most visually impressive of these were definitely the bombards.
The medieval bombard was a massive pipe constructed of wrought-iron rods or bronze. which fired a very large-but relatively light-ball of stone.
The barrel of a bombard was usually set into a solid block of wood, which would hold the weapon steady and absorb the considerable recoil. This design was far from easy to move, however. For transport, the bombard had to be lifted bodily onto a heavy wagon. To support the weight of the gun, the cart usually ran on disc-like wheels which, whenever the cart was canted over to one side, threatened to collapse and dump the contraption to the ground again. In game terms, wagons carrying bombards are limited to flat, clear terrain. They can be moved up or down hill only on well-paved roads, and then only if the hill has a rise (or fall) of less than 1" for each 24" horizontally.
Historically, bombards came in virtually all shapes and sizes. The statistics given here refer to an "average" bombard. If players and/or referees agree, larger or smaller bombards may be used.
 Bombardment Engine Statistics
Engine Type 	AD 	Hits	Range 	Crew	Rate	Move
Ballista 	12 	8 	1"/27" 	3 	1 	6"
Bombard 	3d12	10 	18"/40"	2 	3 	2"
Cannon. light 	2d12	8 	1"/36" 	1 	1 	6"
Cannon, heavy 	2d12	10 	1"/36" 	2 	2 	6"
Catapult, light	2d10	10 	15"/30"	4 	2 	4"
Catapult, heavy	2d12	15 	18"/36"	6 	3 	3"
Catapult, arrow	2d6 	8 	6"/18" 	3 	3 	4"
Trebuchet 	3d12	20 	24"/48"	8 	4 	Nil
The burning properties of the gunpowder used in early cannon was inconsistent at best (quality control wasn't particularly strict). leading to a significant chance of misfires. European artillerists soon learned their lessons, and guns became much more dependable. For game purposes, however, the risk of misfire should be quite high. This will lessen the desirability-and hence the significance of gunpowder-fired artillery, which might otherwise come to dominate the game.
Each time a bombard fires, there is a 10% chance of a misfire. If the weapon itself has suffered any hits, any rolls on the misfire table below suffer a +1 modifier. If the weapon misfires, roll 2d4 and consult the following table:
DieRoll	Result
2-3 	Weapon "hangs fire"
4-6 	Powder burns irregularly: automatic scatter
7-9 	Weapon explodes
A result of "hangs fire" means that the gunpowder has simply failed to ignite, or has failed for one reason or another to explode properly (perhaps it just flared up, without enough force to expel the ball). The weapon must be reloaded.
A bombard that explodes is destroyed. Any figure within 1" of the weapon suffers 1d4 hits with no armor check allowed.
The flame, smoke and noise associated with a bombard frequently panicked pack animals, and even mounts that hadn't been trained to handle the chaos of war. In a fantasy world, this would also be true for troops composed of "primitive" races or creatures who would normally fear fire and thunder. In game terms, lesser-trained cavalry-those units with a morale equal to or less than 10-are sus. ceptible to morale effects. The susceptibility of other troop types is left up to the players, or to the DM.
Each turn in which a susceptible unit is within 4" of a bombardfriendly or enemy that fires on that turn, the unit must make a morale check with a bonus of +2 to the roll (bombards are frightening, but not that frightening). Susceptible troops will not rout towards a firing bombard.
The impact of a bombard shot was so great that it would smash splinters from any hard surface it hit. This "shrapnel" was so lethal that it frequently caused as many or more casualties than the actual shot itself. To represent this, each time a bombard shot strikes rock or stone (either a wall or a horizontal stone surface like a paved courtyard). each figure within 1" of the impact point suffers an attack of AD 10. Obviously, to be affected the unit must be on the same side of a wall as the impact point. Firing a shot against the exterior of a keep will do no splinter damage against on troops within that keep.
A bombard shot has a 45% chance of scattering: scatter distance is 1d4". half that (rounded up) if the range is 12" or less.
===Cannon===
As with bombards, cannon came in many designs. These ranged from "pocket cannon" with barrel lengths of little more than one foot, to monsters that fired shot weighing 100 pounds. Of these bizarre guns, the most appropriate for siege warfare were the 48-pounder full cannon (our heavy cannon) and the 24pounder demi-cannon (our light cannon).
Introduced in the late Fifteenth Century, the full cannon was a highly effective weapon, devastating against stonework and lethal against "soft" targets like troops. Although the full cannon never disappeared, the demi-cannon swiftly became the preferred weapon for use in siege batteries. Round for round it performed almost as effectively as its larger sibling, while weighing little more than half as much, consuming half the charge of powder, taking up less space in the batteries and being much quicker to load.
Both were smooth-bore muzzleloaders, with homogenous bronze barrels no more than eight feet long. They could be transported and loaded with relative ease, and they fired wrought-iron cannon balls. French gunsmiths improved the basic design by casting two trunnions, or prongs, into the barrel just forward of the center of gravity. These prongs rested almost directly over the axle of a two-wheeled gun carriage. The barrel of the gun could be easily elevated or depressed around the fulcrum formed by the trunnions. For traversing. the trailing end of the gun carriage was lifted from the ground and swung to right or left.
The chance of a misfire was lower for cannon than for the less standardized bombards, but the chance still did exist. Each time a cannon fires, there is a 5% chance of a misfire. If the weapon misfires, roll 2d4 and consult the table below. If the weapon itself has suffered any hits, all rolls on the misfire table suffer a + 1 modifier.
DieRoll	Result
2-3 	Weapon "hangs fire"
4-7 	Powder burns irregularly:automatic scatter
8-9 	Weapon explodes
A "hang fire" result is the same for cannon as it is for a bombard. Similarly, cannon have the same chance to panic animals and primitive troops that bombards do. Cannon rounds which strike a stone or wooden surface create large sprays of shrapnel, just as bombards do. Be sure to read the section on bombards if you are firing one or more batteries of cannon in the battle.
A cannon that explodes is destroyed. Any figure within 1" of the weapon suffers 1d4 hits in the case of a full cannon or 1d3 hits for a demi-cannon (no armor check allowed).
A cannon shot (either kind) has a 10% chance of scattering: scatter distance is 1d2", half that (rounded up) if the range is 15" or less.
===Catapult===
Catapults of various kinds have been in use for millennia. From simple, hastily-improvised devices-small trees that could be bent then released to cast projectiles-the catapult evolved into mechanically sophisticated wheeled devices used to great effect by the Romans and later forces.
Although the actual source of the weapon's motive force ranged from flexible beams of wood (shades of the bent tree) to torsioned ropes, the device depended on leverage to propel projectiles. The very nature of the device made it somewhat difficult to adjust elevation. On smaller devices, the rear of the frame or base could be raised or lowered, but on larger examples this was impossible. The only method of altering the range of the shot was to change the amount of torsion or modify the weight of the projectile. Neither of these were particularly precise., making the catapult a notoriously inaccurate weapon.
The construction of the catapult also constrained its role. In most cases, it could only be used as an indirect fire device, similar to a modern howitzer: the shot would are high, and then fall on the target. The only exception to this was when the catapult was so close to a wall or building that the missile struck its target before it reached the apex of its trajectory.
Although they were usually used to hurl rocks or other heavy projectiles, there were no practical restrictions on what could be fired from catapults. The most common "alternative" loads were quantities of small stones, gravel, and even lengths of chain. This medieval shrapnel was next to useless against "hard" targets such as walls and the like, but it was brutally effective against "soft" targets like troops. In game terms, a catapult-light or heavy-loaded with this kind of shot does no damage against structures, but all damage against units is multiplied by 1.5. Thus this kind of load is useful for "sweeping the battlements" of defenders before an assault.
Catapults can also cast flaming missiles, or even canisters of Greek fire. Typically, these projectiles are much lighter than the usual loads used (it's hard to set fire to a rock, after all), but considerably more susceptible to crosswinds; thus the effective range is halved, and the chance of scatter is doubled (although the scatter distance is halved as well). Flaming loads do no damage to structures from their impact, although they have normal chances of igniting flammable materials. Rules for igniting targets are covered on page 86 of the BATTLESYSTEM™️ rules. Against units, however, flaming loads do inflict damage from their impact alone. This equates to an AD of 2d6 for both light and heavy catapults.
Enterprising commanders can use their catapults with more unpleasant loads, of course. During the siege of Minas Tirith in J. R. R. Tolkien's Lord of the Rings, the orcs fired the heads of slain defenders into the city. These examples of nastiness are devastating to the morale of the enemy, and must be dealt with on an individual basis.
The chance of scatter is 40% for a light catapult and 50% for a heavy catapult. The chances drop to 25% and 35% respectively if the catapult is loaded with small stones or the like. The reason for this is simply that you don't have to be as exact with a scattering round as you do with a solid one. Just as you don't have to be as precise with a modern shotgun as with you do with a rifle to hit your target. Scatter distance is 1d3". If the catapult is being used against a wall or building (direct fire) and the range is less than one quarter of the catapult's maximum range, the chances for scatter drop to 15% for light and 25% for heavy. and the scatter distance is 1d2".
===Catapult, arrow===
Many weaponmakers throughout the ages experimented with large weapons that fired multiple arrows or spears with great force (and usually abysmal accuracy). These were mostly ineffective. against structures (those few that were useful in such a role have been subsumed under the category of ballista) but quite lethal against massed troops. In game terms, all engines of this type do no damage against structures.
One design that actually seemed to work comprised a rack holding four or so large arrows perhaps the size of javelins. Behind this rack was a sheet of flexible wood that could be bent backwards. When this sheet of wood was released, the upper portion would snap forward and "slap" the butt ends of the arrows, firing them forward.
The actual number of arrows shot from one of these devices varied from two or three to as high as a dozen. The statistics given are for an "average" device, shooting four or five projectiles. (Weapons doing more or less damage can be used if players and DM agree.)
A shot from an arrow catapult has a 60% chance of scattering. Scatter distance is 1d3".
===Trebuchet===
As they built larger and larger catapults to fire ever-increasing loads, military scientists soon reached the limits of standard catapult technology. There was just so much force that could be generated from bent wood or torqued rope. Luckily for the weapon designers-and unluckily for those on the receiving end-there was another force that could be used: gravity. While gravity doesn't work quite the same in the AD&D game universe as it does in our own (see the SPELLJAMMER™️ boxed set for details), the trebuchet still functions in the same way.
While standard catapults depended on the potential energy tied up in bent or otherwise stressed materials, trebuchets used the potential energy contained in a heavy weight. On one end of the trebuchet's long arm was a sling or basket to contain the load. On the other, across a fulcrum, was a mass of metal or rock. To load the weapon, the crew pulled the basket end down, which raised the countermass off the ground. When they released the arm, the countermass fell, accelerating the basket and load.
Some very large trebuchets were built and used. Theoretically, the only limits to their size and power were the strength of the material used and the amount of mass that could be lifted by the crew.
Since they were such simple machines, trebuchets were usually built on-site. This meant that they were difficult if not impossible to move, and thus to aim. In game terms, once a trebuchet is positioned, it can only fire directly forward, or within 5 degrees to either side of its center line. Range could be varied by changing the mass of the load, the weight of the countermass, or the distance that the arm was pulled down.
As with other catapults, trebuchets could be loaded with many small stones for use against "soft" targets like troops. In game terms, a trebuchet loaded with this kind of load does no damage against structures, but all damage against units is multiplied by 1.5 (rounded down).
Trebuchets can also cast flaming missiles, or even canisters of Greek fire. Typically, these projectiles are much lighter than the usual loads used, but considerably more susceptible to crosswinds; thus the effective range is halved, and the chance of scatter is doubled (although the scatter distance is halved as well). Flaming loads do no damage to structures from their impact, although they have normal chances of igniting flammable materials. Rules for igniting targets are covered on page 86 of the BATTLESYSTEM™️ rules.) Against units, however, flaming loads do inflict damage from their impact alone. This equates to an AD of 2d8.
The chance of scatter for a trebuchet is 55% (their lack of accuracy was balanced by the impressive damage they inflicted when they did hit). The chance of scatter drops to 40% if the trebuchet is loaded with small stones or the like. Scatter distance is 1d6".
===Crushing Engines===
As their name implies, crushing engines transmit and concentrate the efforts of the troops using them against structures with which the devices are in direct contact. For example, the small battering rams described on page 82 of the BATTLESYSTEM™️ rules are crushing engines. Their larger brethren are more massive, more destructive, and often comprise mobile canopies or other structures to protect the troops using them. They are usually wheeled.
At least eight figures are needed to move a crushing engine at its full speed of 3" per turn. Four to seven figures can move it 2", and two or three can move it 1". Crushing engines can only be moved over clear, flat terrain (including roads, but not trails). Twice as many figures are required to move a crushing engine up even a gentle slope (1" rise for every 12" of horizontal distance), and movement up a steeper incline is impossible.
A crushing engine gets two attack dice of the appropriate size for each figure helping to operate the device. At least two figures must be available to operate it, and no more than four can contribute to the crushing engine's attack strength. The engine must be touching the surface to be attacked before it can cause damage.
All crushing engines make use of the same terms and concepts. which are defined below:
Hits is a two-number entry because, in most cases, a crushing engine is enclosed within a structure (generally a heavy wooden roof supported by a framework of timbers) that provides protection for the device as well as for the figures (maximum of four) that are operating it. The first number represents the number of hits that the engine itself can withstand before being destroyed; the second is the number of hits that the protective framework and roof can withstand. This framework must be destroyed before the device inside can suffer damage. Troops under this framework are totally protected against attacks from directly above, and gain a -2 bonus to AR against missile attacks launched from ground level.
In certain cases, players might use crushing engines that do without the protection of a framework.
These would have a single "hits" number, representing the device itself. Troops operating the device are unprotected.
AD columns show the size of attack die (4-sided, 6-sided or 8sided) used when the engine is attacking a certain type of material. The number of attack dice rolled is determined by the number of figures operating the device, as described above.
 Crushing Engine Statistics
EngineType	Hits 	Stone	Metal	Wood
Ram 	6/18 	4 	6 	8
Bore 	12/18	8 	6 	6
===Ram===
In this context, a ram is a long wheeled gallery. Slung from the roof beam by chains is a large log. This log is frequently capped with a heavy metal end-piece to increase its impact and damage. Historically, this end-piece was often shaped like the horned head of a ram, hence the device's name. Under cover of the protective roof, troops could swing the log to strike with great force against a wall or gate.
This design of ram, where the log is suspended by chains, is much more efficient than the "standard" troop-carried battering ram improvised from a large log. For one thing, the troops had to expend no energy simply holding the ram off the ground, and could concentrate all of their might on swinging the heavy thing: thus heavier rams could be used. Also, once the ram had been swung back, simply releasing it to swing forward would cause considerable impact; if the troops added their strength to the forward swing of the ram, the impact could be staggering. This increased efficiency is reflected in the statistics listed above. This kind of ram applies one AD for each figure operating the device. In comparison, troop-carried rams apply one AD for each two figures involved.
The galleries protecting the rams were often elaborate enough to qualify as small buildings in their own rights. As such, their destruction can inflict damage on the troops operating the rams, as discussed on page 85 of the BATTLESYSTEM™️ rules.
===Bore===
Bores (also called "sows") resembled rams in construction: a long, wheeled gallery protecting the central mechanism, which is suspended from roof beams. This central mechanism is usually a log, suspended in slings so it can turn about its long axis. The metal headpiece is a large screw bit, designed to chew through stone.
These engines were designed to be used in one of two ways. In some, the log was pulled back and swung against the target like a ram. Because of the twist to the screw bit, the log would turn a little on impact. Eventually, the bit would bite into the wall and do some damage. This is similar to driving a screw by hitting it with a hammer: not the most efficientway of doing things, although it eventually gets the job done.
The second design has the same log suspended in slings, with the same screw-bit headpiece. Here, however, the log has stakes of wood or metal driven into it along its length to act as handles. In this design, the log isn't swung; using the handles, troops push the bit against the wall and turn the log so that the bit eventually bites. This is more like using a screwdriver.
The galleries protecting the bores were often elaborate enough to qualify as small buildings in their own rights. As such, their destruction can inflict damage on the troops operating the rams, as discussed on page 85 of the BATTLESYSTEM™️ rules.