This article is about the military power of grown dragons. The armies depicted in fantasy literature often resemble ancient and medieval armies, and a dragon's military strength will be considered with these kinds of armies in mind. Armies equipped with cannons and muskets, which appeared during the late middle ages, have not been considered in this article.
A dragon's military capabilities are related to its physiology. Consequently, I have devoted a separate (albeit brief) section to dragon physiology, based on information from multiple sources. The article also relies on the depiction of dragons in the movie Dragonheart (1996), in which their military capabilities were demonstrated. Examples will also be drawn from the fantasy world of A Song of Ice and Fire (ASOIAF), whenever applicable.
Although there seems to be a consensus as to the main characteristics of a western dragon, there are still details which differ from source to source. There are no absolute text-book answers to what a dragon really is or what it can do, so certain conclusions or assessments may not be relevant in some dragon-populated fantasy worlds. Certain statements in this article are also based on assumptions and speculations. However, many premises have been presented in the first sections, and this information makes it easier to see the deductive relationship between premises and conclusions.
This article is based on the western dragon with membrane wings, scales, long bodies and four legs (species classification: Draco Aer).
These intelligent dragons can fly and they have light-weight, membrane, hollow-boned wings. Because of the dragon's size and weight, they have very strong flight-muscles near the chest area to create sufficient thrust. For easier 'take-off' they often jump off from higher cliffs. Some dragons also have magic flight-powers to help them stay in the air for longer periods of time.
Typical flight speeds are perhaps exemplified by Draco (Dragonheart), who flies at over 35 miles/hr (56 km/h) (RC96), but he can reach much higher speeds when diving. It is believed that dragons can reach a flight altitude of over 49.000 feet (15.000 m), by using warm air currents (1). Full-grown dragons can easily bear the weight of a grown person during flight.
Their skeleton is tough but probably hollow in order to reduce weight (2). They have very strong jaw-muscles and the jaw-pressure is probably comparable to or higher than a crocodile's, whose jaw-pressure is 3-5 tons per square inch. Their jaws can be dislocated for swallowing larger chunks of food, just like a snake.
For protection, most parts of their body is covered with overlapping, smooth, tough scales. The scales on the chest area are tougher than on any other part of the body, and it is said that these scales can withstand arrows, bolts or the blow from a sword. A dragon's underbelly and limbs, on the other hand, are softer and represent the most vulnerable spots on a dragon, with the exception of its eyes and its membrane-wings which heal very slowly.
A dragon's average life-expectancy can be measured in centuries (3), although most dragons are killed or succumb to diseases, or die of other non-natural causes. Many of the dragons of House Targaryen in ASOIAF were bred for war, for example, and they were killed in battle.
Their size seems to be related to age: It is said that Balerion the Black Dread from ASOIAF, for example, who was 200 years old when he died, "could swallow an aurochs or mammoth whole". It is also said that some dragons never stop growing (4), but sooner or later they will no longer be able to fly because of the excessive weight. And a dragon which can no longer fly will probably die unless it is fed. Dragons eat meat (sometimes only cooked or charred), but they supplement their diet with plants.
Balerion was exceptionally large though, and a typical full-grown dragon would probably be much smaller. Furthermore, dragons in ASOIAF which live out in the wild could grow larger than dragons which were kept in captivity. Draco, who might be representative for a typical, grown dragon, is 18 feet (5.5 m) high, 43 feet (13.1 m) long and has a wingspan of 73 feet (22.3 m).
Some dragons are capable of camouflaging themselves due to their 'chameleon'-powers. Generally speaking, dragons also have empathic and telepathic abilities which enables them to read the emotions of humans or other animals, or cause fear among their enemies. Their regular five senses are very sensitive as well. However, the dragons in ASOIAF are one of the exceptions, and these dragons do not seem to possess chameleon-powers or telepathic abilities. A dragon with skull horns uses them for infrasonic communication or to amplify roars.
Protection against Close Combat Arms
Whether the scales of a dragon can withstand the blow from a sword, axe or mace depends on several factors, two of the most important are: a) The bodypart being hit, b) The nature of the blow.
In order to reduce weight, a dragon is unevenly protected and its strongest scale armor covers the chest area (similar to a modern main battle tank). In other words, as long as it faces its foe it stands a better chance of deflecting blows.
The actual strength of the chest scales as compared to traditional armor of bronze or iron is unclear, but it is known from empirical tests (RG94) that traditional armor offers sufficent protection against slashes or thrusts from lighter swords and spears. If the chest scales are comparable to iron armor, then only powerful slashes from heavier swords or axes could potentially harm the dragon. The chances of inflicting damage is much better against the dragon's softer limbs and underbelly.
A mounted soldier armed with a heavy lance, would pose a much greater danger to a grounded dragon, because of the higher speed and mass. A flank assault by a lancer could be fatal, because the lance could easily penetrate the thinner scales and softer tissue covering the belly.
Close combat with small arms against a dragon is quite academic, because, under most circumstances, a dragon would never allow a foe within striking distance. A dragon would prefer to keep them out of reach, or stay in the air and sweep down on its foes.
Protection against Arrows & Bolts
Please note that all the ranges mentioned in the following section refer to the weapon's direct fire range across a level ground. The ranges will be shorter when fired diagonally or upwards against a flying target (or longer when fired downhill).
Arrows from conventional bows lack the power to penetrate bronze or iron armor (RG94), but arrows or bolts fired within effective range (650-900 feet, 198-274 m) from powerful composite bows, longbows or crossbows, could harm a dragon's limbs or belly. Bolts fired from powerful crossbows are capable of penetrating chain mail, and these weapons had a theoretical range of about 1.100-1.300 feet (335-396 m). The probability of getting hit beyond this range would be minimal.
However, even an arrow from a conventional bow could inflict damage to a dragon's large wing membranes, the most vulnerable part of a dragon (apart from its eyes). If the arrow does not cause serious injury, it could still cause practical problems because of the gash (lack of lift).
Protection against Field Artillery
Compact field artillery, such as ballistas or scorpions, have sufficient power to inflict serious injury to a dragon, even if the missiles hit the dragon's thick chest area. A heavy 10 pound (4.5 kg) missile or bolt would stun, rip the dragon's wings apart, or, in a worst case scenario, impale and kill the dragon instantly, due to its higher kinetic energy. These machines also had almost twice the theoretical range of longbows (RG94).
Field artillery offers higher lethality, but lower accuracy and rate of fire compared to bows or crossbows. Rigid machines could only hit targets in the direction they were facing, and trying to redirect the fire in another direction would be far too slow against a flying dragon. Non-rigid machines with a wider angle of fire would be far easier to aim, but the curved trajectory would still make it hard to hit objects at longer ranges.
A dragon has several potential 'weapons':
The sharp teeth are perhaps the dragon's most basic weapon, and their penetration or crushing capability is dictated by their enormous jaw-pressure. Its large jaw and sharp teeth pose a serious threat at close range.
Foot claws can be used for ripping or slashing, or for grabbing and lifting an object (in the same manner as a bird of prey). A fully grown dragon can probably lift up to several hundred kilos. Heavier objects can be lifted by flying over the object and grab it using the hind legs. Draco, for instance, was able to lift a horse and two grown people using its large hind claws, and transport them several miles.
The wing claws are mostly used for defense, to slash at a nearby enemy. Because of their relatively fragile wing-structure, this kind of defense is seldom used.
Their whipping or sweeping tail is quite powerful and could easily stun or kill an opponent at close- or medium-range. The spade at the end of the tail is particularly lethal, as it can be used to cleave or cut objects or prey with devastating force. But the tail is less efficient during flight, because the body (which serves as a counterweight) no longer has a firm grip on the ground.
The fire breath, which is analogous to a large flamethrower, is one of the most powerful weapons in the dragon-arsenal. The heat is intense and the range can be measured in tens of meters, although ranges may vary depending on the dragon's size. Draco had a range of about 30-60 feet (9-18 m).
Draco also had the ability to concentrate its fire into smaller fireballs which could be hurled towards objects at greater distances (maximum horizontal range is probably up to 300 feet or 91 m).
A dragon is, of course, unable to breathe flames indefinitely (5), which means that larger, longer flames will exhaust its 'reservoir' more quickly. Proper dosage can therefore be very important in fights or battles.
This section deals with a dragon's offensive capabilities against different kinds of units.
Massed light infantry represents one of the more formidable threats or defenses against a dragon, because of their missile capability. As mentioned earlier, a single missile would not pose a grave risk to a dragon, but heavier missile volleys from light infantry could easily hit and damage the wings if fired from well within effective range. A skilled medieval archer could fire 6 aimed arrows per minute on average: Consider an army with light infantry support consisting of 1.000 archers, for example. They could fire coordinated volleys of 1.000 arrows every 10 seconds , or 6.000 in one minute. Even a dragon would instinctively shy away and keep its distance from such intensive fire.
A dragon can close in on its target at over 50 feet/s (15 m/s), which means that the infantry will only be able to fire two volleys after the dragon is within effective range and before the dragon is within fire-breathing distance (6). Shorter intervals with smaller volleys (500 missiles every 5 seconds for example), depending on how the troops are sub-divided, will therefore provide higher firing rates at the cost of lower firepower.
In order to sustain this suppressive and protective fire, the archers will need to rely on a plentiful supply of arrows. Running out of ammo against a regular army would not be that fatal, because of the support and protection from other types of units, such as cavalry or heavy infantry. But dragons would pose a constant threat which cavalry or heavy infantry would be unable to suppress due to their lack of long range offensive capabilities, and consequently the importance of light infantry is strenghtened when fighting dragons.
Some dragons can hurl fireballs several hundred feet, although they would still be outranged by missile troops. If a dragon is able to get within range and hurl such a fireball, it would cause havoc among packed infantry troops. Non-massed troops or smaller groups would be less vulnerable to such attacks, but at the same time they would also represent a weaker threat to a dragon.
In order to inflict as much destruction as possible, a dragon should strafe enemy units from the flanks by flying parallel to their frontline. Attacking from this angle would also make it harder for the infantry to concentrate its fire.
Heavy infantry lacks a proper offensive option against flying dragons. Their armor and defensive formations will protect them (more or less) against the dragon's claws and tail, but not against its fire breath. Heavy infantry also lacks mobility, and as soon as they break formations and start to flee, they would be easy prey for a dragon in pursuit.
Rear or flank attacks will always be preferable to frontal attacks against these units, and a dragon would under most circumstances prefer this line of least resistance whenever possible. Certain heavy infantry formations may lack sufficient articulation to prevent a successful attack against their weaker flanks. Sudden rear attacks can have a devastating psychological effect as well.
If a dragon has exhausted its fire, it needs to resort to physical shock action, a discipline in which massed heavy infantry excels. The dragon can conceivably perform a low-swoop and try to grab a soldier with its claws, but such low fly-bys will expose its underbelly and wings to throwing spears. Repeated attempts of this kind could be risky, and probably outweigh the 'reward' of killing one soldier. But if a dragon successfully grabs a soldier and lifts him into the air, nothing prevents it from dropping him on his own troops from high above.
Light cavalry may have the same missile capabilities as light infantry, but they usually lack the accuracy and concentrated firepower of light infantry. But neither light cavalry nor light infantry would stand any chance against a dragon in close combat.
Their high mobility and skirmishing tactics can be valuable against regular armies, but their mobility is of limited use against faster dragons. A manned horse can reach speeds of 30 miles/hr (48 km/hr), while a dragon can fly at speeds of at least 35 miles/hr (56 km/hr).
That is not to say that their mobility is useless, because the relative speeds will still make room for some evasive maneuvers. And by combining evasive mobility with somewhat coordinated missile attacks, light cavalry could still pose a danger to swooping dragons.
A fundamental problem seems to be related to the horses, because even battle-trained warhorses would most likely get scared by a large, roaring, sweeping dragon. Horses are easily scared by huge elephants for example (7) or unfamiliar scents. A panic-stricken horse would obviously be of little use as a weapons platform.
Heavy cavalry and light cavalry share some of the same properties when fighting dragons: Mobility and the possibility of panic-stricken horses, although heavy cavalry is slower and less mobile than light cavalry. Because heavy cavalry lacks offensive long-range capabilities, and because their shock action would be virtually useless against a faster, flying dragon, they would essentially be reduced to defensive units. And as such, they would be far less efficient than massed heavy infantry. Their size and lower mobility (compared to light cavalry) would make them good targets for a fireball-hurling dragon as well. The dragon could burn the mounted man at close range or simply grab him, crush him with its jaws, or kick him off the horse.
The previous sections have looked at dragons versus different types of units from an isolated standpoint, but how can a dragon be used tactically against an army, consisting of different kinds of units working in tandem?
In certain fantasy worlds, such as ASOIAF, dragons are rare and precious, and this will often dictate how dragons are used in battle. Sending the dragons ahead of the army as skirmishers against a strong, missile-equipped enemy will only expose them to unnecessary risks. A better solution might be to use them as reserves and leave the offensive to conventional weapons.
Dragons (or other kinds of units for that matter) can be devastating if sent into battle at the right moment: When the battle is in a stalemate or when a decisive opportunity arises. The idea is to let the less valuable regular forces take the brunt of the enemy attacks or counterattacks, and then send in the dragon later.
The mere presence of a dragon may also cause concern among the enemy troops. As long as the dragon stays nearby, the enemy can not simply ignore it, and extra precautionary steps will need to be taken. Dragons can also be used as a tactical surprise or as a deception mechanism. Under certain circumstances, it is therefore better to not let the enemy know of the dragon's presence at all.
Against smaller and less prepared armies, without long-range offensive capabilities, the risk of sending in the dragon ahead would be much lower. The dragons could partake in the initial assualt as shock-weapons to disrupt enemy formations and frontlines, thereby making it easier for friendly troops to exploit enemy gaps.
Dragons can have a demoralizing and psychological effect on enemy forces. Undisciplined or 'green' units may simply start to flee at the rare sight of a dragon. Even disciplined troops may feel demoralized by the presence of dragons, although experienced veterans usually stay and fight, at least until they have suffered significant losses.
A dragon is highly suitable for pursuing a beaten, fleeing enemy. Because dragons can fly faster than a galloping horse, they can even pursue fleeing cavalry. The risk would be minimal, because fleeing soldiers tend to drop their weapons in order to get rid of excessive weight which slows them down. Their morale and fighting spirit would also be broken, and they would be very easy prey for the dragons.
A dragon can not inflict serious structural damage to stronger fortified positions, such as a stone castle, and its tactical role as a siege weapon would consequently be limited, but it can still pose a threat through indirect means.
Its flying abilities obviously makes it easier for a dragon to fly past the ramparts and attack or suppress the defenders, making it easier for friendly forces to scale the walls. But apart from hurling fireballs, a dragon would need to fly close to the walls to threaten the defenders, exposing itself to enemy fire from arrows or heavier missiles. A dragon flying close to the enemy strongholds could also prove counterproductive for friendly siege artillery trying to avoid blue-on-blue incidents.
Stones or heavier objects could be dropped from the dragon's claws or by its rider (if any), but this method would be less destructive or effective than a powerful siege weapon, such as a catapult or trebuchet. Even if a dragon is able to lift heavy objects weighing several hundred pounds, it would still need to fly relatively low (for improved accuracy), exposing itself to missile fire. The accuracy would also be dictated by the rider ("drop on command") or by the intuition of the dragon. A dragon's role as the counterpart to today's fighter-bomber would probably be more effective on the open battlefield against mostly unprotected units.
However, lightly defended and smaller strategic positions without missile defenses can be quite vulnerable to aerial attacks from dragons. If the fortifications are built of wood they can easily be set aflame by the dragon's fire breath.
Another dragon is perhaps a dragon's worst enemy, because two of its primary advantages, flight and high mobility, can now be challenged. It is also conceivable that certain kinds of dragons can be bred or trained for this very purpose, in the same vein of modern air-superiority fighters whose single task is to destroy other aircraft.
A fight between two dragons would most likely resemble an aerial dogfight between two World War I-fighters. Dragons hurling fireballs at each other is in many ways similar to a dogfight between machine gun-equipped WWI-fighters.
Even if none of the dragons could hurl fireballs, factors such as speed and altitude (energy advantage) would still be of importance. If a dragon manages to close in on its opponent undetected, it would gain a precious initiative and an important element of surprise. A successful initial sweep attack could put the opponent on the defensive or even disable him. To improve the chances of success, the dragon can, for example, attack from behind and above or dive out from the sun.
There are many ways a dragon can disable another dragon: One effective means is to rip or tear apart the wings of his foe. Dragons can set an opponent off-balance by ramming him with his claws from the sides or rear, or by grabbing his tail with his teeth. Fire-breath can come in handy against dragons who lack resistance to fire.
Skilled fighter pilots stress the importance of aggressiveness in air combat (RS95), and the same goes for dragon versus dragon encounters. If a dragon does not get stunned or disabled by a surprise attack, it must try to regain the initiative through aggressive maneuvers. The fight will then probably evolve into an aerial ballet in which the dragons try to swoop down onto the flanks or rear of each other. If one of the dragons somehow loses its foe from sight, it would stand at a disadvantage which could prove fatal against an experienced foe. If a dragon is injured or hopelessly outmatched, it can try to seek refuge in the clouds (if any) or on the ground.
A single ship will have problems defending itself against a dragon, because of lacking maneuverability and lacking firepower. A medieval warship would typically hold a crew of up to a few hundred men equipped for boarding of enemy vessels. Only a portion of these would be archers.
The sails and rigs are some of the most vulnerable spots on a ship, and they also restrict the archer's field of fire unless they are lowered. Therefore, a dragon should attempt to set the sails aflame, preferably from a distance using fireballs. If the dragon is unable to hurl fireballs, they could attack from the bow or stern at a steep angle (to minimize the enemy field of fire) and then break off almost vertically without deviating from the line of attack. The dragon would need some altitude in order to efficiently perform this kind of attack: Higher dive-speeds reduce the amount of time the dragon has to linger in the danger zone.
Some medieval ships were equipped with towers, both fore and aft, and these manned towers represent a potential threat to a swooping dragon. Before attacking the sails, a dragon could attempt to attack or destroy these towers first. After the dragon has disengaged, it must watch its tail for incoming missile fire. It should try to figure out in advance the least risky disengagement path. Sometimes the best way to disengage is to simply fly in a straight line away from the target, without resorting to lots of fancy turns and movements which only reduce the speed.
Attacking a ship from the broadside, however, is not a very good idea: The sails do no longer restrict the field of fire, and the crew is therefore able to concentrate more firepower along the sides of the ship.
More ships complicates the issue. The dragon has to be careful and avoid getting exposed to several broadsides or 'killing sacks', areas in which missile fire can easily be concentrated. The ships, on the other hand, have to watch their background when firing, in order to avoid friendly fire. A dragon would still retain its mobile advantage, and could easily outmaneuver the ships and hit weaker or undefended spots. A dragon would, of course, pose an even greater threat if assisted by a friendly fleet.
Dragons would be very useful as reconnaissance units. Their height above ground will enable them to see far longer into the distance than a person on the ground, and their superior mobility will let them inspect specific areas more carefully in a shorter amount of time. A scouting dragon can prove invaluable when an army is moving through enemy territory. However, the potential drawback is that a flying dragon will also be easy to spot by the enemy.
Superior mobility also comes in handy when sending long distance messages: Messages or letters can be sent from place to place by a trained dragon. And there is no risk of getting eaten by birds of prey which is often the case with trained birds.
Some dragons can be mounted, which is analogous to a pilot flying a plane. Trying to direct the dragon from the ground is obviously much more difficult. The effectiveness of a dragon can be vastly improved in this manner, because a rider will be able to tell the dragon exactly what it wants it to do. The dragon may need training in order to understand the signals from its rider, but dragons should be relatively easy to train because of their intelligence.
(1) It sounds farfetched that a dragon could reach an altitude of 49.000 feet (15.000 m) without suffering from hypoxia. In humans, symptoms of hypoxia may begin at as low as 5.000 feet (1.500 m) and collapse may occur at 17.000 feet (5.100 m). On the other hand, a dragon may have a significantly different metabolic rate or even magical abilities (a rather 'cheap' explanation) which enables them to reach such extreme heights without blacking out. In practice, regardless of maximum theoretical 'service ceiling', a dragon would most likely prefer to stay closer to the ground in order to breathe more easily.
(2) With real-world physics in mind, I strongly doubt that a grown dragon would have been able to get off the ground at all because of the lift-to-weight ratio, without using some kind of flight-magic (which some dragons do seem to possess). A dragon might have been able to stay afloat or glide after jumping off a cliff, but only for a brief amount of time. However, dragon-literature is at least aware of the problem, and it tries to provide reasonable explanations for dragonflight, based on the premise that a dragon could actually fly.
(3) Life expectancy must not be confused with life span. Life expectancy is related to the average age of an organism before it dies of disease, starvation or predators. Life span refers to the maximum age of an organism before it dies of natural causes. The aging-process of certain animals, such as crocodiles and sharks, is very slow or non-existent. MK97
(4) "A dragon never stops growing, so long as he has food and freedom" Arstan to Dany (A Storm of Swords - ASOIAF).
(5) The amount of firebreath is related to the amount and digestion of food in a dragon's stomach. The food is digested in two stomachs, and the leftover food is turned into a byproduct of hydrogen, which is stored in large glands for later use. Hydrogen is mixed with other chemicals (from the dragon's body) inside its lungs, and the mixture burns when it comes into contact with oxygen.
(6) Typical effective range: 650 feet (198 m). Dragon flight speed: 50+ feet/s (15 m/s). Infantry reloading time: 10 seconds. First volley at 650 feets distance to target, and second volley at 650-(10 * 50)= 150 feet (46 m), 10 seconds later.
(7) Hannibal, the brilliant Carthaginian general, often used war elephants (with mixed results) in battles not only to break enemy fronts, but also to scare enemy horses.
(MK97) Visions: How Science Will Revolutionize the 21st Century (1997), Dr. Michio Kaku.
(RC96) Dragonheart: Collector's Edition DVD, Universal (1999), Audio Commentary track by director Rob Cohen.
(RG94) The Great Battles of Antiquity (1994), Richard A. Gabriel & Donald W. Boose, Jr.
(RS85) Fighter Combat: Tactics and Maneuvering (1985),Commander Robert L. Shaw.