Advice for Fantasy Writers

This article is by Toni Šušnjar.

One of basic elements of fantasy warfare is fantasy army. And one of basic elements of army is its size, which will affect organization and logistics, as well as strategies and tactics it can employ. Thus, prospective fantasy writers should understand factors which limit the size of premodern militaries. But to understand that, it is first to understand differences in what writers mean when they talk of armies.

Army vs Field Army

Basic difference one has to understand is that of military versus army versus field army. Latter distinction is especially important, and often difficult, as both can be described as simply “army” in sources and thus it is necessary to rely on contextual clues.

Military is the overall armed forces of the country. It can include

Army or ground forces is the overall land-based forces that the state can control.

Field army is a formation of land forces, that is, a portion of land forces deployed as a coherent force under single commander with the aim of achieving a goal. Therefore, a country can simultaneously deploy several field armies, which may or may not be under command of a higher commander, depending on the requirements.

But as noted, “army” can be used much more widely. Roman navy for example was organizationally a part of the Roman army, so when one reads of the Roman army it is necessary to keep track of whether navy is included into it or not. Even terms can have varied meanings, as “field army” in late Roman context can mean either an actual field army – that is, army in the field – or else the collection of soldiers that may be deployed as a field army but will not necessarily be deployed in a single group. In this article, I will be using it in the former context unless noted otherwise.

This is important to keep in mind when writing of the numbers. Country can never deploy its entire ground forces into a single, massive field army, for several reasons:

1. Number of available soldiers will always be lesser than the number of soldiers listed on the rolls. Some soldiers may be sick, injured, or otherwise unavailable. Bureaucracy also takes time to record losses, so there will be period during which dead soldiers may still have been retained on the rolls. And in centrally-organized paid armies, commanders may keep soldiers on the rolls to pocket their pay. While this may be handled by use of reserves – units having more soldiers on the rolls than the field formation strictly requires – it means that maximum realistic military establishment will always be closer to 85% – 90% of the paper numbers, and maybe even as few as 60%. For example, while ancient writers report 600 000 men in the Late Roman Army, modern historians estimate that actual establishment was closer to 400 000 – some 67% of the paper strength.
2. Contingencies must always be made. Another enemy may appear, enemy army may slip past the deployed field army or armies, and one must not forget that in premodern states army was often responsible for security against bandits and such – city watch and other pseudo-police organizations only acted within the city walls. For these reasons, much of the army had to stay “at home” at all times.
3. Logistics. As size of the field army increases, so the difficulties of feeding it increase as well. Premodern armies attempted to live off the land whenever possible, and for many states there simply was no other option as they did not have the administration to organize supplies beforehand.

This is the mistake that Mark Whittow makes in his “Making of Byzantium”, confusing field armies for the total military establishment, and detachments of units for entire units. He thus concludes that field armies of 18 000 – 25 000 men are inconsistent with total force of 120 000 men. Whittow’s conclusion is as follows: field armies in Germany and Byzantium largely exceeded 10 000 men, and even the largest Byzantine field army did not exceed 25 000 men. For this reason, Whittow argues, any attempt to argue for 120 000 strong Byzantine army is unconvincing and Byzantine military must not have numbered more than 30 000 men. Yet as will be shown below, size of field armies is governed by concerns significantly different from those of total military manpower, and two have little relation to each other.

Fantasy writers however often fail to understand both the distinction between the total military and field army, as well as limitations that practicality places on size of either or both. Thus it is not impossible to find armies of hundreds of thousands traipsing the countryside or total military in millions. One example of this is Fire Emblem: Awakening, where Walhart is said to have a million men in his army, and several hundred thousand men show up for a single battle.

The primary determinant of the size of the country’s military as well as the size of field army or armies it may deploy is its nature. Generally speaking, increased professionalization leads to reduction of a total number of soldiers available for deployment (size of the military) but increase in number of soldiers that can be deployed as a coherent body (size of the field army).

Size of Military

Size of the overall military depends fundamentally on several factors:

1. total amount of resources available (manpower, food, finances)
2. proportion of resources that can be used for the military
3. amount of resources required for each soldier

As noted before, increased professionalization of the army results in increased amount of resources required per soldier, in part due to increased requirements in terms of equipment and other expenses, and in part due to opportunity costs as increased time soldier spends training and fighting means that he gives less to the community in terms of economic input.

One noticeable aspect of premodern professional armies was that they liked round numbers and standardization. Roman legion was divided into units numbering 6, 60, 600 and 6 000; or else 80, 480 and 4 800 – depending on the period. From the end of 5^th until the end of 6^th century all Byzantine field armies were divisible by 5 000 – which was a standard size of Byzantine meros (division). And this principle of standardization remained a major aspect of Byzantine military organization all the way until 1084. Each Byzantine theme (military province) had army size divisible by 1 000. Between 840 and 867, Byzantine army’s payroll came to exactly 20 000 (Byzantine) pounds of gold. Similar principle of standardization is also noticeable in the ancient Assyrian and Macedonian armies.

Reason for this was simple practicality: professional army is a bureaucracy, and having standardized unit sizes makes calculations and logistics much easier in time before the electronic computers and a massive caste of well-educated bureaucrats. It only took calculating payroll for one unit, and then multiplying that sum over the entire army. Moreover, having units organized on basis of 6, 8 or 10 allowed troops to quickly adapt to serve in the 6 / 8 / 10 deep battle line.

At any rate, before one attempts to estimate size of the military, it is first necessary to estimate population size. This can be done by multiplying area of the country or feudal property one is trying to estimate army size for with the population density. This however changes with climate and the time:

• Byzantine Empire: 7,95 people per km2 in 775, 8,00 in 842, 8,18 in 959
• Population of France:
  • area: 551 500 km2
  • 5 500 000 in 1 AD = 9,97 per km2
  • 5 500 000 in 400 AD = 9,97 per km2
  • 5 000 000 in 600 AD = 9,07 per km2
  • 5 000 000 in 800 AD = 9,07 per km2
  • 7 000 000 in 852 AD = 12,69 per km2
  • 9 000 000 in 1000 AD = 16,32 per km2
• Population of England:
  • area: 130 279 km2
  • 1 500 000 in 100 BC = 11,51 per km2
  • 4 000 000 in 50 AD = 30,7 per km2
  • 2 800 000 in 200 AD = 21,49 per km2
  • 3 600 000 in 400 AD = 27,63 per km2
  • 1 000 000 in 500 AD = 7,67 per km2
  • 1 600 000 in 1000 AD = 12,28 per km2
  • 1 710 000 in 1086 AD = 13,13 per km2
  • 1 800 000 in 1100 AD = 13,82 per km2

Professional Army

Roman Army is the quintessential standing army of the antiquity (by comparison, Persian army was organized more along feudal lines). And for its time, Roman army was massive. Under Tiberius (14 – 37 AD), Roman army numbered some 125 000 men, and as many men in the auxillia, for a total of some 250 000 men. In addition to the army, Roman military also included the Praetorian and urban cohorts of Rome (10 000 men) and 40 000 marines in the navy. Empire at the time may have had population of 45,5 million people, which gives proportion of 0,55% of population serving in the army and 0,67% for the military in total. By 235 AD, Empire had 35 legions, for a total of 385 000 men – this is confirmed by 285 census of 389 704 men.

The height of the Roman army was likely under Constantine I. During this period, Roman military may have had as many as 645 000 men (335 000 legions, 228 000 auxilliaries, 18 000 Praetorian Guard, 64 000 navy). Yet population may have actually reduced to some 39,3 million people, which will have lead to a proportion of 1,64% of people serving in the army. More likely number of 55 million people however would give a proportion of 1,17% of people in the army. Using John Lydos’ number of 435 266 men for army of Diocletian would give proportion of 0,79% of population in the army.

Highest proportion of full-time soldiers was in 395 AD, at some 2% of the population. After that it dropped: in 559, Byzantine army numbered 150 000 men, which even at lower population estimate of 20 million would still have been 0,75% of the population.

Territorial Defense Army

After the great disasters in the 7^th century, Roman army was transformed into an essentially territorial defense force – the theme system. Out of the earlier field army of 150 000 men of the Eastern Empire, perhaps some 80 000 had managed to withdraw to Anatolia and settle there on grants of land (stratioka ktemata) provided by the Emperor. This number of soldiers remained constant until 774 at least.

As fortunes of the Empire improved, so did the army increase. Byzantine army numbered some 120 000 men in 840 AD, of whom some 32 000 cavalry, 74 000 infantry and 8 000 marines. It should be noted however that the Imperial Tagma – fully professional, personal army of the Emperor – had 16 000 cavalry and 8 000 infantry. These were organized into four tagmas (regiments) of heavy cavalry and two tagmas of infantry, each tagma being 4 000 men strong. This may have been to ensure a more rapid response, but also because heavy cavalry had greater fighting power than infantry, and thus a cavalry-heavy army was better at putting down any revolts of the themes. Themes themselves had differing strengths, but these were always in the thousands. According to al-Jarmi, the Armeniacs and Anatolics themes had three turmarchs while the Bucellarians and Thracesians had two.

By 959 AD, Byzantine army had expanded to 144 000 men, of whom 88 000 infantry. The zenith of Byzantine military expansion was achieved in 1025 AD, when Basil II could count on 250 000 soldiers – though not all of them were necessarily combat effective.

These numbers can be compared to population estimates of the Empire:

• 775 AD = 7 000 000
  • 80 000 troops = 1,14%
• 842 AD = 8 000 000
  • 120 000 troops = 1,5%
  • of those 24 000 full-time professionals = 0,3%
• 959 AD = 9 000 000
  • 144 000 troops = 1,6%
• 1025 AD = 12 000 000
  • 250 000 troops = 2,08%

As can be seen, overall number of troops relative to size of population in a thematic system can still vary widely depending on several factors: percentage of the land set aside for the army, proportion of fully professional soldiers with no land, and composition of the army (proportion of infantry versus cavalry, proportion of heavily armored troops). All of that depends on climate, terrain and generally how rich the society is.

For example, typical value of land for Byzantine thematic troops was as follows:

• light cavalry = 4 pounds of gold = 180 modii (?) = 535 140 m2; 1 lb = 133 785 m2

• cataphract = 16 pounds of gold (72 solidi per pound = 1 152 solidi) = 30 families = 720 modii (2 140 560 m2)
• infantry = 50 modii (9^th century Byzantine) – 148 650 m2

In 840 AD, military lands accounted for some 20 – 25% of the arable land, while by 1025 this had increased significantly. And it is in fact possible to see exactly how much through a simple calculation:

• 840: 8 000 000 population = 1 360 000 households = 136 000 000 000 m2
  • 96 000 themata
    • 5% cataphracts = 4 800 = 10 274 688 000 m2
    • 15% light cavalry = 14 400 = 7 706 016 000 m2
    • 80% infantry = 76 800 = 11 416 320 000 m2
    • TOTAL: 29 397 024 000 m2 = 21,62% of arable lands
• 1025: 12 000 000 population = 2 040 000 peasant households = 204 000 000 000 m2
  • 200 000 themata
    • 5% cataphracts = 10 000 = 21 405 600 000 m2
    • 25% light cavalry = 50 000 = 26 757 000 000 m2
    • 70% infantry = 140 000 = 20 811 000 000 m2
    • TOTAL: 68 973 600 000 m2 = 33,81% of arable lands

Thus a writer aiming to recreate Byzantine military organization simply needs to do the steps in reverse: find out amount of military land, relative number of troops, and from that, their absolute numbers. But since Byzantine military organization was detailed, exact and very regimented, this “simply” can end up involving a lot of complex research and calculus.

An example would go like this:

• Population of the empire / kingdom = 5 000 000
• Urbanization rate: 15% = 85% rural population = 4 250 000 peasants
• Rural households: 4 250 000 / 5 = 850 000
• Holding per household = 0,5 – 1 pound of gold (75 000 – 150 000 m2)
• Army composition: 5% cataphracts, 15% light cavalry, 80% infantry
• “Batch” of 100 men:
  • 5 cataphracts = 80 pounds of gold = 80 – 160 families
  • 15 light cavalry = 60 pounds of gold = 60 – 120 families
  • 80 infantry = 80 – 160 families
  • TOTAL: 220 – 440 families
• Military lands: 20% – 35%

Thus a “sample” of 100 men (5 cataphracts, 15 light cavalry and 80 infantry) would require anywhere between 220 and 440 families to support. How many would depend on how rich average peasant household was – a pound of gold of land may have been anywhere between 100 000 and 150 000 m2, and average holding per peasant family was often less than a pound of gold but rarely more than that.

Assuming a poorer kingdom and worse conditions, we get 20% military lands and 440 families to support a unit of 100 soldiers. With 850 000 rural households, this means 170 000 military households and a total of 386 units. Result is maximum number of landed army as 38 600 soldiers. But we also saw previously that in 842 AD number of full-time paid soldiers in Byzantine Empire was exactly 1/5 of the landed troops, and to this one needs to add also some 42 000 men of the Navy or 0,5% of populace (number of 899) though this number may need to be halved for poorer kingdom. End result thus leaves us with total military of 58 320 (38 600 landed troops, 7 720 standing army, 12 000 navy), or a total of 1,17% of the population.

With rich kingdom, we get 35% military lands and 220 families to support a unit of 100 soldiers. Again using 850 000 rural households, this reults in 300 000 military households and a total of 1 360 units. This leaves number of landed troops as 136 000. Using again same numbers as previously, this force also leads to 27 000 full-time soldiers and 25 000 sailors. Total military is thus 188 000 (136 000 landed troops, 27 000 standing army, 25 000 navy), or a total of 3,76% of the population.

Of course, these are the extreme examples, and especially the high-end example calculated previously is unlikely. In reality, inefficiencies in the system would somewhat reduce all of the theoretical numbers listed above: not all land listed as military land will be in use at the same time, and many soldiers would have fiefs larger than the prescribed values used in the calculations – sometimes significantly so. Commanders may also keep some of the dead soldiers on the roster in order to collect their pay. For historically likely numbers, it is best to consult the estimates of the Byzantine army strength cited previously, or else cut the numbers calculated from land by some 15 to 25 per cent (meaning that end range would be 0,9% to 3,2% of the population).

This article continues in the next post (on 11 April 2024) and focuses more on the size of feudal European armies. That post also includes references for further reading.

About the Author

Toni Šušnjar is an amateur historian and fantasy enthusiast with interest in ancient and medieval history as well as Medieval and High Fantasy, especially warfare. He also writes War Fantasy blog.