Castles and Siege Warfare

When I was a kid, medieval warfare fascinated me. Compared to today's forms of combat, medieval warfare was simpler, more personal, and less destructive. Everyone wore plate or mail armour and flailed away at his opponent with his sword. It was full of heroism, chivalry and honour.

That's what I thought at the age of 12, anyway.

The conduct of battles was certainly simpler than today but the majority of combatants were armed with spears — later, pikes and other polearms — not swords. Knights usually wore metal helmets and leather armour underneath mail surcoats. The lower class warriors, if they had any armour at all, wore either leather or quilted wool coats, padded for extra protection. This was far different from the armoured knight that most kids imagine when they think of medieval warfare. In fact, the heavy plate armour that you see in museums are usually from the early Renaissance era. Schools did little to change this impression, focusing as they do on people, names, and dates, not the details that make history fascinating.

One area that I found sadly lacking in school was the strategic aspect of medieval warfare. Why did anyone bother to lay siege to a castle?

The purpose of the castle was to provide protection to an area in the event of war. In medieval times, when war came to an area, the local farmers would retreat to the castle for protection. This was the idea, anyway; in many cases the Lord locked out the serfs and peasants, who were left to fend for themselves. The castle was owned by a member of nobility, or leased to the noble, and it was primarily for the defence of the noble that the castle existed. The garrison could be made up of hired warriors, but was usually made up of local men who owed their lord a certain amount of days a year as a soldier.

Why was a small detachment — often no more than 50 or so men during the main campaining season — sitting in a static fortress so much of a threat? Most castles were on communication and supply lines. Moving through medieval forests was incredibly slow and virtually impossible for carts and sometimes even horses. Fast movement was made along roads. When an army moved, its supply train moved behind it. The supply train carried personal goods of knights and men-at-arms, as well as water and food supplies. Later, it carried gunpowder. Most armies of the period were capable of living off the land by foraging for food but this wasn't always possible or desirable. Supply shipments, though, were prime targets of raiders and particularly vulnerable to enemies who had penetrated an army's rear. This became more pronounced when gunpowder increased in use since gunpowder could not be foraged. It didn't take much of a force to strike the baggage train of an army and destroy it or rob it.

If an army was part of a larger group, having an enemy behind it meant that it was guaranteed to lose any messages sent to friendly units. This would give important information to the enemy and could stop friendly units from reinforcing the army when necessary.

The greatest fear an army had was that of the enemy striking it in the rear. Not only is this of great danger to an army's baggage train, but it greatly demoralized troops. Soldiers are vulnerable from behind. If things go bad in front of them, they need to be able to retreat to a safe area. If the enemy got behind a battle line, the soldiers would be attacked from their most vulnerable side and likely either massacred or captured. The very idea of the enemy penetrating the army's rear was often enough to cause panic.

You don't leave an enemy force behind you, no matter how small. Unfortunately, castles in an enemy's land were always garrisoned during the campaign season. This meant that an attacking army couldn't afford to leave an enemy castle in enemy hands. To give you an idea of what could happen, Tantallon Castle, during the English Civil War, was the home to Moss-troopers, essentially partisans made up of Lowland Scots loyal to the crown. These Moss-troopers attacked the Parliament's armies at night, raiding their supply columns of food and ammunition. As a result Tantallon was besieged, even though there were fewer than 100 moss-troopers. Tantallon wasn't designed to withstand an artillery bombardment. Even so. it took 12 days before the castle to fall. Often, in earlier times, sieges could last for months. Defeat often befell the side that succumbed to disease and hunger first.

A castle's location was its most important feature. It could be defending an important waterway as in Caerlaverock's case, it could be protecting vital land routes as at Stirling, or it could be located at a natural defensive site that spawned a town or village as at Edinburgh. A castle's site follows one of several common themes. Stirling and Edinburgh were built on large mounds of volcanic rock, making access difficult. Tantallon was built on a cliffside with defences built to protect it from attack from the only avenue of approach. Eilean Donan and Urquhart castles were built on the water's edge, Urquhart on a small spit of land and Eilean Donan on an island. Caerlaverock, having been built on flat land, was protected by forest, swamp and an artificial moat.

Border raiders, cattle thieves, neighbouring barons and clans, and pirates all thought twice about attacking a village with a castle nearby. Many castles, particularly on The Scottish Borders, were built simply to keep an invading army busy. The English, it was reasoned, couldn't penetrate deep into Scotland if they had to lay siege to all of the border castles in their way. Well, in fact, the castles weren't that much of an impediment, as they were rarely heavily manned; outside of the campaigning season, a castle might have a garrison of no more than 50 men.

Not everyone was allowed to build a castle. Castles were expensive. 'They often took several years to complete, requiring the work of trained carpenters, masons, plumbers, painters, and architects. Then there were the labourers who actually worked on the castle, digging the foundation, working the stone, etc. A castle had a large support staff, including cooks, salters, brewers, maids, general labourers, and — of course — the garrison. Even if a lord paid these people a pittance he still had to feed and house them. This is not even counting the cost of the materials and the land needed for the castle itself.

Castles were military structures of great importance, and as such the king wouldn't let just anybody build one. It took a royal charter to build a castle. This wasn't as exclusive as it might sound. Over the years loyalties varied, and while a king might grant a charter for an allied baron, that baron's offspring could easily be politically opposed to the king.

To build a castle you needed a chunk of suitable land. This wasn't usually a problem, but castles are few and far between in the West Highlands of Scotland because the terrain isn't flat enough for a large fortification.

Castles were status symbols. A lord with a big castle was, almost by definition, more important than a lord with a small castle, and a clan with two castles was more important than a clan with one. Castles were popular payment to a nobleman who had done the king a service. The regent of King James VI of Scotland was given Dirleton Castle after stopping a treacherous attack on Stirling Castle. It was always better to have castles in the hands of friends than in the hands of opponents.

Once a nobleman has his charter, has enough money for his castle, and has a lot of nice, suitable land where does he actually build his castle? First, there are strategic concerns. Is there a waterway nearby? Is there a road? Merchants moved their goods either by water or by road. If there was a castle nearby, it meant that the route was less likely to be haunted by thieves. This meant that it would be a popular trade route, and would garner tolls. Furthermore, enemy armies were more likely to use a road or river than to travel through wilderness. Was there a prominent hill on the land? Was there a strategic hunk of coastline, or a bluff with a limited access route? Of the nine castles I visited (and several others that I saw during my trip) about 40% were built on hills or volcanic mounds, and 40% were built on waterways or coastlines. Hills were preferred, as it made access by opponent's siege engines very difficult. Interestingly, Dirleton was a much better protected fortress in medieval times than Stirling or Edinburgh. Although they were all on volcanic outcrops, Dirleton was built on a small volcanic outcrop; the other two castles had a large promenade in front of the main gate that allowed the approach of siege engines.

If you're a lord building a castle and you don't have a nice hill to build on, or a cliff to back your castle against, or an island on which you could protect your fortress with water, you have to make do with manmade defences. In other words, you build a moat. This wasn't easy, though, since you had to be near a lot of ground water or your moat would simply dry up. Caerlaverock's moat, while manmade, is naturally filled with water since the castle was built near a swamp. Another, more laborious, option was for the lord to build a hill and then place the castle on that. This was done with Huntly Castle.

Medieval warfare was a pretty simplistic affair. This is particularly interesting when you realize that the Romans had refined battlefield tactics to a science, experimenting with different weapon types, formations, and tactics. Most of this was lost, though, with the collapse of the empire and the disbanding of the professional soldier classes. As a result, warfare during the dark and middle ages was straightforward and without a great deal of refinement. The men of the various lords on each side lined up, the more courageous jostling to get into the front rank. These lines were sometimes up to twenty men deep. When the charge order was given (and often before that), one side (sometimes both) would rush across the battlefield and engage the enemy. That was pretty much it. The loser was the side that ran away first. Not much to it.

A medieval battle was decided by the following factors: initial troop placement; terrain and defensive structures; charisma of the army's leader; the morale, physical fitness and training of the troops; luck. Notice that I left out tactics. That's because there usually weren't any. Joining the army, for a very small few, was equivalent to winning a modem day lottery. If you were lucky, you captured loot or — joy of joys — captured a nobleman, who's family would pay you a ransom for his safe return. Because of this, the use of reserves was almost unheard of, since no one wanted to be the last into a battle and, thus, the last to grab any glory or loot. It also meant that a lord would send his men into battle when he felt it was time, not when the king or general felt it was time. There was little overall command structure. Whenever reserves did enter a battle, they were usually the "small folk" (lightly armed serfs, squires, walking wounded, etc.) who guarded the baggage train. This is exactly what happened during the battle of Bannockburn in 1314, when the English army (on the verge of collapse because of poor initial troop placement, inferior training, and fatigue) routed due to the charge by the Scots "small folk," whom many on the English side mistook for reinforcements.

As the period wore on, technological differences started to have a dramatic effect. An excellent example is the Welsh longbow at Agincourt. By the Renaissance, professional armies were springing up again, and with them came unit formations and tactics. The sword was replaced by the pike and musket, the trebuchet was replaced by the cannon, and tactics and manoeuvres began to decide the outcome of battles.

While medieval set piece warfare was a simple, bloody affair, siege warfare was actually quite complex, scientific, and even ritualistic. And bloody, but not nearly as bloody as a set piece battle. Sieges, in fact, were far more common. Take the Scottish Wars of Independance, for example. There are three quite famous open battles in the war (stretching over some 20 years), though there were many more smaller skimishes. There were, however, something in the order of about 30 to 60 sieges, as castles changed hands several times. Siege warfare was cheaper than an open battle, particularly in manpower. An open battle was an all or nothing, winner-take-all proposition, with high casualties. It was a gamble medieval armies would rather not make. An open battle was usually insignificant strategically. Henry V may have become king of France — after Agincourt — in name, but he didn't become king in fact until he completed a series of sieges afterwards.

The first phase of the actual siege consisted of the army pulling up near the castle, sending a messenger, and asking for surrender. This was a ritual that was almost never skipped. Chivalry dictated that if a castle was surrendered — usually within a required time period — all inside would be free to leave without harassment. This enticement was often enough for someone in the garrison to take matters into their own hands and open the castle gates for the attackers without the commander's permission. If the castle was not surrendered, the inhabitants were at the mercy of the besiegers. In many cases, the leader of the garrison was left without specific orders from his lord as to what to do if besieged, and so the garrison was often allowed to send a messenger to the lord asking him for guidance. If no guidance was given, the burden fell on the garrison commander who — more often than not — would give up the castle. Sometimes a castle would only be surrendered after a relief force failed to arrive within a specific time period. This was the case at Stirling Castle in 1314 which led to the Battle of Bannockburn and Scotland's independence. Sometimes, the very presence of the attacking army was enough for the garrison commander to surrender peacefully.

Assuming that the castle didn't surrender, the besieging army would attack it in an effort to defeat the garrison, or force it into surrendering. This was the siege's second phase. Earthworks and defensive palisades were built around the castle by the attackers, and siege engines would be commissioned. The castle would be assailed, rammed, mined, sapped, shot at, and burned in an effort to breach the walls and storm the garrison. This could go on for months, but usually ended within a few weeks, either because the garrison was defeated or because the attackers gave up. Even when the garrison was defeated, soldiers captured as prisoners were often dealt with mercifully as they were "just following orders." The commanding officers, though, were usually executed.

The third phase began only after the attackers gave up attacking the castle. The attackers would retreat out of missile range from the castle and try to starve out the defenders. Occasionally disease ridden carcasses were catapulted into a castle in order to promote pestilence, and — if possible — a castle's water supply would be poisoned. The siege would thus end after the garrison was starved into submission or died from disease, the attackers gave up due to poor morale, lack of supplies, or disease, or a relief force came to break the siege. In most cases the attacking force would eventually succeed.

There were many techniques used in attacking a castle. Fire was used extensively until stone castles replaced timber fortifications. Even afterward, fire, usually shot from catapults, was used by both attackers and defenders in an effort to set alight anything wooden.

The simplest, and bloodiest, technique was to send men to the walls with scaling ladders. If they could withstand arrows, boiling water (Hollywood's stereotypical boiling oil was rarely used), stones, knocked-over ladders, and armed defenders, this would work, but the cost in lives was high. Some scaling ladders were mounted on mobile platforms, making them harder to knock over. Also used were baskets mounted on weighted arms that could lift defenders over the walls. These machines tended to be large and carried few men, rendering their overall worth suspect.

More expensive, in time and money, were the use of siege engines. These were usually battering rams and large drills covered with a wood and hide roof and mounted on wheels. An attacking force would roll the engine up, batter at the wall or door, or attempt to drill through the castle foundation. Arrows usually had little effect, but fire was a constant hazard for these engines. So were moats, and crevices, which had to be filled in by exposed labourers before the siege engine could advance to the walls. The most expensive siege engine was the siege tower, a large wooden structure with interior floors and taller than the castle's walls. It would be wheeled up to the walls (once again, after moats and crevices were filled), knocked off its wheels, and set firmly beside the castle. From here, attackers could attack the defenders from a protected location, and could lay a bridge across to the castle's parapet. It, too, was susceptible to fire, though Richard the Lion protected his siege tower during his siege of Acre by plating it with metal.

What we commonly think of as the catapult came in various forms. The idea was to fire heavy objects, usually rocks, at the opposing castle or over the castle walls. Hot coals were a favourite projectile, as they could ignite wood within the castle. One of the most fearsome catapults was the trebuchet. These were very large towers with a big lever on them. One end of the lever held a sling and the other held a box full of rocks. The box end was raised in the air by manpower. A boulder, used as shot, would be placed on the sling below the mid point of the tower. The box would be dropped, and the sling would shoot the boulder at great speed. These weapons were difficult to make, but they could penetrate the stone wall of a castle. After a wall was battered enough, a big enough hole would have allowed attacking soldiers to enter the castle. The trebuchet was fearsome because there was little the castle's inhabitants could do about it, as it fired well outside of arrow range.

Mining and sapping were some of the more successful means of gaining entrance to a castle. Sapping was the procedure by which men, armed with picks and hammers, would attempt to break through the castle's foundation, preferably at the base of a tower. A large covered trench would be cut towards the castle. Once the sappers were at the base, the castle's design often protected the them from attack from they inhabitants. The sappers would proceed to pick away at the tower. As the hole widened, wood was used to shore up the tower. Once enough of the tower was chipped away, the wooden supports were set on fire and hopefully part of the tower would collapse, breaching the wall and letting in the attackers. When the foundations were deep, or the base of the tower could be defended, a mine was dug under the tower, where the sapper's would work underground. Sometimes a mine would be dug into the courtyard of the castle itself and used as an entry point for assaulting soldiers, but this was rare. To this day, British Army combat engineers are known as sappers.

The defenders of the castle had tactics of their own. The primary defence was the castle's layout. Stone walls replaced the early motte and bailey fortifications that were made of wood. The stone was very hard to destroy from a distance and offered the defender a great deal of protection. Siege engines had trouble getting to the castle if it was surrounded by a moat or a sat on a hill or rock. Slits in the walls allowed a defender to fire arrows at the enemy. These slits were wider on the inside than on the outside, giving the defender a wide area of fire while offering a very small target for enemy archers. Later gunloops (holes for guns) were built into castles.

As threats of a siege mounted, hoarding would be installed on the castle walls. These were wooden enclosures that jutted out over the edge of the wall. They protected the defenders while allowing them to drop things on the attackers. Catapults continued to improve during this era, so castle walls grew taller and taller in response. Square towers tended to have blind spots that made defence difficult, and they were particularly vulnerable to sapping, so round towers soon replaced square towers. The most vulnerable part of a castle was the gate. To protect what was otherwise a wooden door covering a hole in the wall, gates were often built between two small towers. The gate defences could include wooden and metal portcullises, arrow slits aimed towards the insides, and trap doors for dropping things on attackers unlucky enough to be trapped behind the gate. Once inside, the attacker might encounter a set of inner walls, manned by a second set of defenders.

The attackers weren't the only ones with engines. One particular engine used by defenders was the "crow," a large, weighted arm with a rope and hook attached at the end. It was used to scoop up unwary attackers and pull them into the castle, where they could be interrogated or, if of noble birth, ransomed.

To defend against mines, defenders would counter mine. Counter mining either meant digging a mine underneath the attackers' mine and then sapping it, or digging a mine into the attackers' mine, thus giving the defenders a sally port. Sally ports were also built into the castle's design. These small openings would allow a defender to launch a ground attack against the attacker. This could work well if the attacker was into the "starvation" phase of a siege and unwary. If the attacker was prepared, though, the defender could find himself trapped outside of the castle, with disastrous effects.

The city of Constantinople fell to the Turks in 1453, heralding the end of castles and walled cities as it was known until that time. This is because the city fell after its walls had been breached by the Turk's bombards. Gunpowder created a major change in siege tactics. High castle walls designed to stop catapults and trebuchets were particularly vulnerable to pummelling by artillery. Some castles were retrofitted with gun ports, but the attackers almost always had bigger guns which they used to pound the castle into submission.

Constantinople fell in 1453 but castles were still in use for another 200 years, though they were being slowly phased out by artillery forts with their low walls and artillery batteries. The last big gasp of castle warfare occurred in the 17th century. European armies laid siege to each other since it was a cheap way of fighting, until the great strategist Gustavus Adolphus reintroduced the world to manoeuvre and tactics. The English Civil War saw the ruin of most of Britain's castellated strongholds, as well as the last use of the siege tower.

With few exceptions, every ruin I visited in Scotland was put into that state of disrepair during the English Civil War. Those few ruins that held out beyond this period were destroyed during the two Jacobite rebellions in the 18th century. Today, only Stirling and Edinburgh castles are still in use as military installations. The other intact castles, such as Eilean Donan, Balmoral, Glamis or Flores, are either reconstructions or homes of the aristocracy. Still, it's the ruins that I prefer with their crumbling walls and broken towers. Here, your imagination runs free and if you try hard you can just make out the roar of guns and the clanking of armoured men.