Zombies and the science of siege warfare

May 11th, 2007

When sitting down to a horror film, I invariably plump for a zombie film. I think it’s because it’s so hard to imagine how a shambling, rotting corpse could be a threat to anyone, but somehow it always ends up this way. I was intrigued by how many films depict survivors barricading themselves in makeshift fortresses, only to await their eventual demise. As a fan of medieval warfare (perhaps it’s all these castles here in England), I also recognised how the principles of siege warfare didn’t support defence against an undead threat.

In the context of this essay, we’ll assume for the most part that our enemy is the classic zombie - undead, slow, of low intelligence but possessed with reasonable strength and unlimited stamina. I’ll also be assuming second-generation epidemiology for these creatures - rather than servants under the control of a mage, our zombies are of biological genesis and their epidemiology follows a viral pattern of infection - the recently deceased may awaken, and infection spreads through bites and exhibits 100% infection and mortality rates, resulting in a exponential morbidity pattern within the human population. Now, onto medieval warfare…

A siege occurs when a defending fortress refuses to surrender and cannot be easily taken by a frontal assault. The attacking army block both the escape of the defenders and prevent reinforcements and supplies reaching the besieged army. Thus, a war of attrition develops, and if neither army can gain a significant military advantage, the result is often decided by famine or disease.

Traditionally, the attacking army will attempt to circumnavigate their target’s defences by infiltration, sapping (tunnelling under walls to collapse them), artillery bombardment or siege engines (battering rams, trebuchets, etc). Given the typically low intelligence of zombies, sophisticated siege weaponry and tactics are unlikely, although rudimentary coordinated attacks are sometimes seen - the setting of an ambush in Return of the Living Dead, for example. Also, the danger of infiltration must not be underestimated, as a single zombie inside the fortress can quickly escalate into a catastrophic situation (28 Days Later, Night of the Living Dead).

There are four possible outcomes to a siege. Firstly, the defending army are rescued by an outside force, who defeat the encamped aggressor (both the 1683 Siege of Vienna and the 1899 Siege of Mafikeng ended this way). This is probably the outcome that most survivors of zombie attacks are hoping for when they decide to take refuge in an abandoned shopping mall or old house. In the early stages of an outbreak, rescue by local police or a militia is fairly likely (Night of the Living Dead, Children of the Living Dead). However, as time passes, not only does the likelihood of rescue diminish, but the zombie threat increases, entrenching the defenders in their hastily-assumed position.
Secondly, the defenders may chose to engage the attacking army. Historically, this almost always ends in the annihilation of the defenders - who, by definition, are not organised for open combat. However, even after a protracted siege, Soviet forces were able to force a break in the German encirclement during the 1941 Siege of Leningrad. In fiction, attempts to break sieges are often taken by heavily-armed defenders fighting their way out of a fortified compound (Dawn of the Dead, Night of the Living Dead). However, there exists a narrow window of success for this strategy, as over time the zombie army perpetually grows in size while the resources of the survivors are diminished.
The third outcome of a siege is that the attacking army exhaust their resources and are defeated by starvation or disease. Clearly, this is extremely unlikely with a zombie threat. Lifespan of a zombie is uncertain, ranging from around two months for the sub-living (28 Days Later) to months and maybe years, depending on conditions. Even with this limiting factor, survivors must have resources (food, water, medicine) within the compound to outlast the undead threat.
Finally, and most likely, is that the besieged army succumbs to starvation or disease, and is overrun by the attacking army. Only the most well-prepared defender can hope to outlast a significant zombie outbreak, and even then must rely upon the eventual second death of the zombie army. In addition, the threat from within must not be underestimated as the strain of a long-term siege takes its toll on the mental stability of the survivors. Infighting can quickly lead to sectarian violence as survivors divide into broad classes (28 Days Later, Land of the Dead). This is compounded by the inevitable influxes of refugees (Dawn of the Dead) as smaller, nearby fortresses are overwhelmed by the attacking force. These refugees will not only tax the limited resources of the defenders, but bring the threat of infection into the compound.

So what is to be done in the event of a zombie outbreak? For small scale threats, it is almost always better to organise a militia and meet the undead face-on. When under attack by a limited force of zombies, the undead threat should be contained and destroyed. The predilection of zombies to congregate can be used to the defender’s advantage here, typically by luring the attacking army into a killzone (Return of the Living Dead Part 2, Chopper Chicks in Zombie Town).

However, in the event of a larger outbreak, or where resources do not permit an organised militia, survival strategy favours small, mobile groups that can evade zombies forces and relocate easily once a position becomes untenable (28 Days Later). Much in the same way that the ability to deliver huge destructive power (aerial bombardment, ICBMs) made well-fortified static defences obsolete in the early 20^th century, the resistance of zombies to hunger and exhaustion, and their unique biology that allows unrestricted population growth, renders any long-term advantage of siege to nil. In order to survive a zombie outbreak, readers are encouraged to concentrate on remaining flexible and highly manoeuvrable, retreating quickly to areas of low population density, and to seek contact with greater military force.

Of course, in the event of a major zombie outbreak, the global fall of mankind to the walking dead is almost inevitable, so a noble last stand may be preferable to those of a cinematic inclination.

Entry Filed under: General

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