The Nitpicker’s Guide to Ancient Warfare: Sieges

By David Flin

This series of articles is the first draft of what will hopefully be a book published by Sgt. Frosty Publications

Depiction of the siege of Lisbon, 1147 by the painter Alfredo Roque Gameiro

The details of how sieges were conducted are the subject of a later chapter. I shall cover here only the general nature of sieges; why they were often key battles.

Fortified positions are a major force multiplier for defensive operations. That’s their purpose. It means that castles and fortified positions can be held with much smaller numbers than are required to take them. Generally speaking, an invader can’t leave enemy-held castles behind without a significant screening force (which diminishes the force available to the invader). An unscreened castle would be able to conduct raids against supply trains to the invading force, causing all sorts of problems.

If the castle is left, the troops can sally out at will at disrupt supply lines; they can fall upon isolated groups out foraging (and they’ll need to forage if the supply lines are disrupted). The threat of forces from the castle force the invaders to remain concentrated, which prevents effective foraging and doesn’t protect long supply lines. The invading army starves. As a result, it has to reduce the castle.

Middle Age warfare generally devolved into a series of sieges. The strategically located Stirling Castle in Scotland was besieged eight times between 1296 and 1357, frequently changing hands between Scots and English; three times between 1571 and 1585; and then in 1651 and 1746. The reason was simply that it couldn’t be bypassed in any invasion.

One of the common aspects of a siege that everyone knows about is the tradition of sparing a city that surrenders quickly, and of sacking a city that resists. This is often attributed to many different groups: the Mongols, the Romans, the Assyrians, the list is endless.

Of course, it was standard procedure. Quite when it was assumed that resistance turned the price of failure to a sacking of the city may vary. One common division was the point when a ram first strikes a wall.

The reason for the difference is treatment of a fallen city comes down to one word. You guessed it: cohesion. Taking a defended city is tough, and any assaulting force is likely to take heavy casualties doing so. These casualties diminish the cohesion of a force and, should it break through, it was almost certainly not going to be under much control. The survivors would be angry, and preventing them from getting out of control would be a tall order.

Shakespeare describes something of this in Henry V, at the siege of Harfleur.

Therefore, you men of Harfleur,

Take pity of your town and of your people

While yet my soldiers are in my command,

While yet the cool and temperate winds of grace

O’erblows the filthy and contagious clouds

Of heady murder, spoil, and villainy.

Fortifications are a significant defensive multiplier. Among those who took this to heart were the Romans. Not so much with city fortifications, but their “marching forts”. The Roman armies developed the habit of constructing fortified marching camps every night when on the march.

The camps didn’t serve quite the same defensive purpose as city walls. City walls are intended to resist a siege; a fortified camp is mostly intended to prevent an army from being surprised and to allow it the time to either form for battle or to safely refuse battle. Function follows form; the defences of a camp are mainly concerned with preventing a stealthy approach, slowing down attackers, and providing defenders with an advantage at relative economy of cost and effort.

Of course, a badly-constructed fort or castle can trap the defenders. The Battle of Arausio (105 BC) provides an example of how badly things can go with a badly sited camp. Specifically, two badly sited camps. Two Roman forces were camped on the Rhone River, to bring the Cimbri to heel in battle. Because of a dispute between the commanders of the two forces, they camped on either side of the river. It took a direct order from the Senate in Rome to get both forces to camp on the same side of the river. Even then, they camped apart.

One of the two forces attacked the Cimbri camp, and got annihilated for their pains. After ransacking the first Roman camp, the Cimbri turned their attention to the other Roman force. Unfortunately for the Romans, this camp had been positioned such the troops found that they had their backs to the river when attacked, and thus no way to retreat.

The Romans lost, according to Livy, 80,000 soldiers and 40,000 servants and camp followers. This was a disaster for Rome on a level of Cannae.

The moral of this story is that it is unwise to place fortifications in a poor location.

Location, location, location.

Fortified positions, be they cities, fortresses, isolated castles, or whatever, need to be well-sited. Typically, they will be sited to guard key strategic points: river crossing points, junctions of trade routes, at mountain passes, near ports, and others.

The inevitable consequence of this was that these fortified positions couldn’t simply be ignored. The whole purpose of the fortifications was to protect the key locations. Which is why so many castles have had a very chequered history.


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David Flin is a writer and owner of Sgt. Frosty Publications. His books can be found there.