Military of Westeros 1 – Organization and Manpower
In A Game of Thrones, Ned Stark states that he may have to “call the banners” in order to deal with the King Beyond the Wall. During the Rebellion, both Robert and Aerys had called banners. There are further references as the War of the Five Kings begins: both Castelry Rock and Riverrun call their banners and start amassing armies below the Golden Tooth. These banners are commanded by lords bannermen, who train, organize and maintain their own private military forces, and send them to their liege lord when called upon. They are also seemingly responsible for upholding the local justice, as Jorah Mormont was exiled after trying to sell some poachers into slavery.
It is thus obvious that Westerosi armies are not standing salaried armies, like those of Free Cities. In fact, Catelyn Stark notes in GoT that “Most of them were smallfolk: crofters, fieldhands, fishermen, sheepherders, the sons of innkeeps and traders and tanners, leavened with a smattering of sellswords and freeriders hungry for plunder. When their lords called, they came… but not forever.”. Hother complains that half the harvest is gone because Greatjon took too many men with him – which is only possible if soldiers actually are farmhands. This is also seen when Jamie thinks about the Westerland host encamped outside King’s Landing, noting that only two thousand were left, the rest having gone home to plant fields and bring in one last harvest (AFfC).
Even so, these troops are disciplined: Northern forces stand against both arrow barrage and Lannister cavalry charge, despite being exhausted and outnumbered. While they break in the end, that is no untrained rabble, regardless of what Kraznys Mo Nakloz claims. However, neither are they professional soldiers such as those of Roman Empire, even of Middle Byzantine period (650. – 1050.). At best, they could be compared to Byzantine thematic light infantry: troops whose job is fighting, but who have other jobs besides it, and thus could not be held in the field forever. While Ser Jorah calls foot soldiers “rabble”, he has a tenous grasp of reality at best, and even professional troops in pre-modern times may have fled if a commander fell (as in the example he uses). Catelyn disparages “untrained peasant boys” which Edmure left to defend Riverrun after taking actual soldiers to the field, again indicating that soldiers are at least part-time professionals. This is also obvious from when Tywin decides to reinforce his army. Host under Stefford Lannister – “sellswords, freeriders, and green boys from the stews of Lannisport” – had to be armed and drilled before being risked in battle. And the very fact that commands can be given during the battle means that armies are fairly professional.
Peasants are seen occasionally to be armed so as to defend fortified places, as seen with Ser Roger Hugg and his six men-at-arms, four crossbowmen and a score of peasants. Such usage of raw conscripts is nothing unusual – historically, Byzantines would arm civilians in cities when necessary, but such militia was never deployed for battle in the field.
Overall, information is rather contradictory, but the position for which most evidence seems to point is that Westerosi armies are mostly professional, if not full-time – they would be similar to militia or US National Guard (or Byzantine thematic forces).
Each lord commands, raises and equips his own forces. This means that lord paramount has to maintain personal relationship with each of his subservient lords, if he expects them to serve. Robb personally hosts his bannermen when they come to Winterfell. This however leads to significant unreliability in assembling the forces. As early as A Game of Thrones, Catelyn has doubts whether her father’s banners will come if called, as Darys, Rigers and Mootons were sworn to Riverrun, yet fought on Rhaegar’s side at Trident, and Lord Frey showed up late. Lord Frey shows up late again during the War of the Five Kings. Starks on the other hand do command significant loyaty from their bannermen. Bannermen are relied on to ready the defenses when necessary, but their freedom of action can easily cause problems, as there is no way to ensure their military competence. This is displayed with lord Edmure Tully, and also when Tyrion muses about the possibility of baiting Stannis’ bannermen into attacking Dorne. Likewise, they are liable to leave main campaign in order to defend their own lands, as was done by Tully bannermen once Lannisters started raiding. And as Stannis notes, bannermen are often inconsistent – even in their treasons. Jamie also states that every great lord has unrily bannermen who envy him his place: Tyrells have Florents, Tullys have Freys, Starks have Boltons; and as soon as these powerful bannermen smell weakness, they rebel.
Lords bannermen also serve at war councils, as advisors. This again is a two-sided blade, as while many would have significant experience, they also have personal interests. And lords – including lords paramount – are often blinded by their pride, as best shown by Renly and Edmure. Edmure in particular forces a completely unnecessary battle while also withdrawing troops that Robb had left at the Twins to ensure Lord Walder keeps his faith. He also sends Lord Bolton to retake Harrenhall. Likewise, Imry Florent gets command due to his social status, but once in command he acts as brainless as average EU MP – he pushes his whole force into a maneuver-restricted area, without a first thought given to scouting ahead.
Personal command style is also different. Robert and Robb commanded their forces from the front; Tywin and Stannis commanded from the rear, better to see what is going on at the field of battle.
Scouts and spies are used to gain information on the enemy, but they are not always successful. Blackfish neutralizes Jamie’s scouts, and Stannis prevents any information about him from reaching Lannisters simply by isolating Dragonstone.
Towns appear to have their own town guards, but these are apparently not used outside the city. Town guards which Brienne encounters in A Feast for Crows wear mail hauberks.
Manpower and organization
When Robb was gathering his forces, Karstarks brought 300 horsemen and 2 000 foot from their castle at Karhold. This raised Robb’s host to 12 000 men. At that point, host had 3 000 armoured lances, of which 300 – 400 knights, making for 25% heavy cavalry. Later on, Ser Wylis and Wendell Manderly lead near 1 500 men: 20 knights, 20 squires, 200 mounted lancers, swordsmen and freeriders, and the remaining 1 200 being foot. Freeriders are unlikely to be armoured, but overall, 16% of force are cavalry, of which unknown percentage are heavy cavalry. Lord Frey commands 4 000 men. Final count of Robb’s army is 18 000 men. Numbers above indicate that a force of 12 000 men would have had 3 000 heavy cavalry (25%), and a force of 13 500 would have had 3 240 cavalry (24%). As such, entire army of 18 000 may have had 4 500 cavalry, or as few as 3 600. Infantry is composed of pikemen, archers and men-at-arms on foot.
After Theon took Winterfell, Ser Rodrik Cassel assembled at least a thousand, perhaps 2 000 men to retake it. “Reek”‘s force with which he betrayed and killed Cassel’s troops numbered between 200 and 400 men, being outnumbered 5 to 1 by Cassel’s force, but was cavalry while Cassel had infantry. Much of Cassel’s force was butchered.
Lord Wyman Manderly proposed to build Robb a fleet of galleys – within a year, sufficient to take Dragonstone and King’s Landing both. But before then, there were only “half-a-dozen longships and two war galleys” commanded by Mallisters at Seagard. Robb had 3 500 men left when returning home after splitting from infantry, suffering losses, losing Freys and dismissing Riverlands forces. But he said that he will have more than 12 000 men after linking up with Lord Bolton and the Freys – which is to say, his infantry. As such, total losses of campaign in the south were 6 000, of which 1 000 cavalry. After the slaughter of the Twins however, only 4 000 men returned North, most of them Dreadford men.
When Stannis is planning his campaign in the North, Jon Snow tells him that mountain clans may be able to raise between 2 000 and 3 000 men to help him. Description makes them out to be basically stereotypical Scottish Highlanders, and all infantry. At another point, man states that mountain clans may be able to raise 3 000 – 4 000 men, but statement is given under interrogation (that is, torture) and thus likely unreliable.
Winterfell itself is guarded by crossbowmen. At Winterfell, Hother Umber had 300 spearmen and 100 archers. Umbers had 400 each, and Karstarks sent 500 men to join Stannis. If these numbers are doubled, it would add 2 600 men.
Wyman Manderly brought 300 men with him, of which 100 knights. He also tells Davos that he had been building warships. Davos sees at least 23 war galleys in inner harbour, but Wyman states that there are more. If there are 50 galleys, that alone would have required 6 500 men. A total of 10 000 thus is not impossible.
Total: 36 000 troops (est. 7 000 cavalry, 22 500 infantry, 6 500 sailors)
This however is possibly an underestimate, as North is very large. In fact, 45 000 ground troops seems likely, latter of which would be about 50% greater than what Torrhen Stark could field. Of those, 10 000 would be cavalry, 35 000 infantry. Region around Winterfell was likely completely devoid of troops, but further-away regions may have close-to-full strength still available. On the other hand, northernmost houses also appear to have deployed significant proportion of their strength.
Renly noted that Robb crossed Trident with 20 000 men, and that, with lords of Trident at his back, he may have 40 000. As such, Riverlands should be capable of deploying 20 000 men or more. Edmure states that “when all (his) strength” is marshalled, he should have eight thousand foot and three thousand horse. Cavalry is again around a quarter (27%). His estimate is supported by Catelyn when she says that Tywin has twice Edmure’s numbers. This is likely a practical limit, due to many lords not showing up as they were defending their lands from raids. Freys in particular did not show up. As such, Renly’s estimate is likely correct.
Total: 20 000 troops (est. 5 500 cavalry, 14 500 infantry)
Riverlands also have an unknown number of river galleys. These are small galleys with nine oars on each side. Such a ship would historically only have crew, with no regularly assigned ground troops. Boat seen in ASoS is commanded by Riverrun’s captain of guards, which may indicate that Riverlands’ galleys are crewed only on a provisional basis, with no standing complement of their own.
Frey camp under Riverrun is a bloody mess. There is no indication of pallisade – unlike e.g. Lannister camp – and general impression is one of chaos.
Lannister troops in battle in A Game of Thrones had 4 000 heavy cavalry on the right wing, and 300 serving as Ser Kevan’s bodyguard. Reserve was 5 000 strong, half cavalry and half foot. Left wing, near the river and on uneven ground, was light cavalry: “mounted archers in leather jerkins, a swarming mass of undisciplined freeriders and sellswords, fieldhands on plow horses armed with scythes and their fathers’ rusted swords, halftrained boys from the stews of Lannisport and Tyrion and his mountain clansmen”. It was a bait, expected to break, and thus explaining the low quality of troops. It still shows that, while Westerosi armies have a lot of professional and semi-professional troops, they also have a significant number of untrained levies – and if even rich Westerlands have such rabble as part of their forces, rest of the Westeros is likely worse. On the other hand, Ser Stafford was expected to properly train his rabble before leading them to battle. One way or another, it does not make sense, as – especially during ten year summer – said “rabble” will be required to work the fields, while taking them off the fields would provide a negligible increase in combat power at best.
Lannister camp under Lord Tywin, which Tyrion joins, is said to have spread over leagues, holding 20 000 men (which is confirmed in A Clash of Kings). Yet only knights had tents; lords “sprung up pavillions as large as houses”, while common men camped out in the open. This shows clear class difference; while such a thing is unavoidable in any pre-modern army, professional armies such as Roman armies (including medieval ones) made certain to equip even common infantry with tents (one tent per eight soldiers – countobernium). However, medieval soldiers indeed often did not raise tents – not because they couldn’t afford to (which is the implication here), but because they were too lazy to do so. When they did raise tents, result was often a disaster – such as when Hungarians placed their tents too close to each other, leaving them helpless against Mongols. Nobles on the other hand would scoot off for falconry during a march.
Camp is also fortified with stakes. While hardly a moated pallisade likes of which Roman armies erected well into Late Byzantine period, it does speak well of organization of the army. So does the fact that latrines are apparently separated from the camp when Tywin’s army is encamped at Harrenhall.
Knights and men-at-arms are separated out, and position of knight is one of honor. This holds with 15th century, by which time knights did indeed become a social class, as opposed to original meaning of heavy shock cavalry.
Jamie Lannister besieged Riverrun with 12 000 foot and 2 000 – 3 000 horse. In ASoS, Lannister camp at King’s Landing numbers 20 000 men, who are specifically noted as Tywin’s army. In AFfC, outriders, mounted archers and heavy horse are listed separately, and heavy cavalry is about a fifth of total (200 heavy horse, out of group of less than 1 000 men).
TOTAL: 35 000 troops (est. 7 000 heavy cavalry, 28 000 infantry)
Martin also stated that Westerlands have strength at sea comparable to Reach. Assuming a total of est. 200 warships would lead to 25 000 oarsmen and 7 500 soldiers.
TOTAL: 67 500 troops (est. 7 000 heavy cavalry, 28 000 infantry, 7 500 marines, 25 000 oarsmen)
Crownlands (incl. Dragonstone)
When Davos goes to visit Stannis at Dragonstone, there were three thousand men camped on the island. This likely did not include sailors of the fleet, which itself consisted of war galleys, carracks and cogs. Later, when besieging Storm’s End, Stannis has 5 000 men, of which 400 horsemen, light horse mostly. Unknown number of those are sellswords which Stannis was already gathering earlier, but Stannis’ own troops most likely number 3 000. Renly states that such a host would not survive the first charge of his vanguard – correctly, as it turns out, although not at the time he had predicted.
Fury, Lord Stannis’ flagship, has 300 oars on three decks, deck covered with scorpions, and catapults fore and aft; the only galley in existence larger than Fury was King Robert’s Hammer, at 400 oars. Other galleys mostly had cca 200 oars. Ser Imry organized his fleet in ten lines of battle, each with twenty ships – normal galley tactics would have had one or two lines of battle, so this is likely a result of the constrained space. Additional 15 ships were lost along the way, so original fleet would have numbered 215 ships. It should be noted that this does not include Lyseni sellsails, which remained outside the bay as a rear guard. Ser Imry is noted to have had “four times as many ships as the boy king”, leaving Joffrey 50 ships. Original Royal Fleet would have thus numbered 265 ships. From example of Fury, and the fact that galleys have oars in multiples of 100, it can be assumed that one deck has 100 oars, or 50 rows. Byzantine dromond had 35 oarsmen on deck on either side and 25 beneath – 35 and 25 rows, respectively – at 32 meters length. As Westerosi galleys have covered decks, length of Westerosi galley might be 50 – 60 meters. Large Byzantine dromond had 230 rowers and 70 marines, and likely 170 oars. Out of 20 ships Davos lists, one has three hundred oars, two have two hundred oars, and 17 have a hundred oars. As Davos had noted nine particularly large galleys at Dragonstone, this disposition can be assumed to have been duplicated in all ten divisions. Assuming disposition similar to Byzantine dromond – two rowers per oar at third deck and one per oar at lower two decks, as well as soldiers as 30% of number of rowers – 300-hundred oar galley would have 400 rowers and 120 soldiers, 200-oar galley would have 200 rowers and 60 soldiers, and 100-oar galley would have 100 rowers and 30 soldiers. This is supported by the fact that Davos’ 100-oar galley is specifically noted to have had 100 rowers. Thus, each division of 20 ships would have had 2 500 rowers and 750 soldiers. Stannis’ fleet – 10 divisions – would have had 25 000 rowers and 7 500 soldiers. Original Crown fleet of 260 galleys would have had 32 500 rowers and 9 750 soldiers.
City Watch had 2 000 men during Robert’s reign, though these were not truly soldiers. Number was eventually expanded by Joffrey to 6 000, though most of them were useless. Tyrion had 300 “knights, squires, men-at-arms) at King’s Landing in addition to City Watch, though these may have been Lannister troops, as well as 800 sellswords.
RPG game endorsed by George Martin gave Crownlands 10 000 – 15 000 men, however. Rhaegar had 40 000 men, of which 10 000 were from Dorne and maybe 10 000 from Reach and 5 000 other loyalists, with Crownlands likely at 15 000 men. As such, division would be as follows:
- Mainland: 12 000 infantry, 3 000 cavalry
- Narrow Sea: 4 600 infantry, 400 light cavalry
TOTAL: 62 250 troops (16 600 infantry, 3 400 cavalry, 9 750 marines, 32 500 rowers)
Stannis’ host at the Wall included knights, freeriders, mounted bowmen and men-at-arms. Fact that mounted bowmen were present indicates that Westerosi armies are professional – mounted archery is an extremely difficult skill to master, and requires either a culture built around horse archery (e.g. Mongols) or a highly professional military (e.g. Byzantine Empire). He also manages to shatter a wildling host of 30 000 men with a force of maybe around 2 000 – after Blackwater, he had 1 300 – 1 500 men at Dragonstone and 300 at Storm’s End.
When marching for Winterfell, his army manages to cover 22 – 24 miles per day before the snows start falling. This is more than even Roman army could cover with a forced march, and indicates that his entire force was likely mounted – and using mules carrying supplies instead of wagons. Fourteen miles a day is considered a slow pace, reinforcing the conclusion. Yet Asha is riding in a wagon – which ought to have reduced marching rate to 20 kilometers (12 miles) per day, or half the marching rate here. At any rate, this is clearly a professional force.
Ser Balon has in his entourage “three knights, eight squires, twenty men-at-arms”. Stannis’ troops included knights, squires, servants, men-at-arms, spearmen, axemen, archers.
When Theon visits his father Balon, he sees at least fifty or sixty longships, though the fact that Euron’s Silence was not there may mean it is only a portion of the strength of Iron Islands. Theon himself muses that aboard longship each man is a king, and Iron Islands are called a land of ten thousand kings; this is likely an exaggeration. Lord Goodbother came with forty longships; this house is one of more powerful in Iron Islands.
Longship Theon receives is of apparently average size, smaller than flagships. It is hundred feet long, with fifty oars and deck enough for a hundred men. However, longship may not have had that many men. Historically, a longship with 30 rowing chairs would have been 30 meters in length with crew of 70 – 80 (and 60 oars – snekkja had 20 rowing benches and 40 oarsmen). Thus, a hundred-feet longship (30 meters) with 50 oars would have had 25 benches, 50 oarsmen and crew of 60.
Victarion took with him nine-tenths of the Iron Fleet in A Feast for Crows. When Aeron looks over the bay, “a hundred banners lifted and began to flap”. In A Dance of Dragons, 93 remaining ships of the Iron Fleet (out of a hundred) sail to Essos; as such, Iron Fleet itself may have somewhere around 100 ships.
Margaery Tyrell states that “a thousand ships” are attacking the Shields, though Merryweather states that “some fool had counted double”. Captain of the Huntress stated that “hundreds” of the ships afflict the shores, and that without Redwyne fleet, they cannot be stopped.
TOTAL: 500 ships, 30 000 men (?)
Asha manages to gather 40 longships, which is “not near enough” to throw off Crow’s Eye. Harlaw is one island out of seven. There were “hundreds” of longships at Lord Hewett’s Town. Asha states in ADwD that The Crow’s Eye has summoned all the strength of the Iron Isles to Old Wyk, but this contradicts the statement that Iron Fleet has 100 ships. Victarion sets sail with 99 ships eastwards, yet campaign in Westeros continues. Iron Fleet having 100 ships is confirmed later. These were apparently thrice the size of a common dromond, which would place them at 150 oars and crew of maybe 180.
Ironborn at Deepwood Motte under Asha had cavalry; her force numbered 100 men. In total she had four longships and less than 200 men when she was sitting in the North; this would indicate that total longship crew should be less than 50, potentially reducing crew estimate to 25 000. However, this was a result of the losses, and losses in men may have been either greater or lesser proprotionally than losses in ships.
TOTAL: 500 ships, 42 000 men
Stormlands and Reach
Renly Baratheon, with “power of Storm’s End and Highgarden” behind him, managed to assemble an army of 100 000. When Catelyn arrives at his camp, we see thousands of cookfires, horse lines, staffs holding banners, great siege engines, pavillions and pikes. There are also swineherds and camp followers. Renly later notes that he has 80 000 men (twice Robb’s number) with him, with another 10 000 at Highgarden, and a strong garrison at Storm’s End.
What is interesting is what there is not in this initial overview of the camp. There is no indication of the pallisade, let alone a ditch and a rampart that would have been standard in Byzantine camps. It is also weird that siege engines are easily noticeable – normally, siege engines, especially large trebuchets, would be disassembled for transport. And instead of proper training for mass combat, Renly is holding a tournament. His own tent is as luxurous as a small villa, with a lot of completely unnecessary things, including a high harp and a pair of hunting hawks. When dining in a hall later, guardsman was slouching. All of this shows that Reach host, while numerically impressive, is much less professional than armies of North, Westerlands or Crownlands. As Catelyn notes, “they are boys drunk on song and glory”. In fact, Reach is modeled after Medieval France, whose knights tended to be extremely undisciplined and ruined more than one battle by charging in without plan or in spite of one (see “Tactics” section).
At parley with Stannis, Renly notes that his foot is coming behind him, “a hundred thousand swords and spears and pikes”. He also apparently had “near all the chivalry of the South”. While this is less literal and more figurative, it is indeed possible that Renly had deployed vast majority of power of two kingdoms. Stannis later gives a number which can be assumed to be far more accurate, having being told to Davos in privacy, and by a person much less flamboyant – Renly left 60 000 foot at Bitterbridge.
When Stannis marches for King’s Landing, his vanguard numbers 5 000. However, Sansa notes that “everyone says” Stannis will have ten times the number of city watch when he arrives. This means his force numbered 20 000 in total. As Renly only took cavalry with him, and a fifth of knights departed – thus about equal to Stannis’ own force – this means that Renly’s total force was 20 000 cavalry and 70 000+ infantry (Bitterbridge + Highgarden), for a total of 90 000 men. Cavalry being 22% of the force is similar to other regions, yet also lower than most. This may also indicate greater proportion of heavy cavalry, Stormlands having unusually low proportion of cavalry and thus offsetting advantage of Reach, or possibly both.
TOTAL: 90 000 troops (20 000 cavalry, 70 000 infantry)
Littlefinger stated that “Margaery brings 50 000 swords with her”. This, in conext of discussion, means only infantry, leaving 20 000 infantry for Stormlands.
TOTAL STORMLANDS: 25 000 est. (20 000 infantry, est. 5 000 cavalry)
TOTAL REACH: 65 000 est. (50 000 infantry, est. 15 000 cavalry)
Loras in AFfC states that Willas and Garlan can raise 20 000 men. This may or may not add to the above totals, but more likely not. Lord Tarly’s patrol which Brienne encounters is “bristling with longbows and lances”, indicating perhaps mounted longbowmen – but they will have been mounted infantry, not horse archers.
Redwyne fleet on Arbor – an island that is part of Reach – is considered the only force capable of countering the Ironborn, even at their lower number of 500 ships. Paxter Redwyne owned two hundred warships and a thousand merchant ships.
House Hightower has “a line of warships, anchored by three big dromonds and Lord Hightower’s towering four-decked banner ship”. They can also raise 20 000 men on their own.
Assuming each division of 20 ships has 2 500 rowers and 750 soldiers like Crownlands fleet, a total of est. 220 warships would lead to 27 500 oarsmen and 8 250 soldiers.
TOTAL REACH: 100 000 est. (58 250 infantry and marines, 15 000 cavalry, 27 500 oarsmen)
Martin stated Vale to be “about equal to North and Dorne”. This would place it at cca 28 000 ground troops. I will round it down to 25 000. This is confirmed by Littlefinger stating that he would not stand a chance against Royce’s 20 000 troops.
TOTAL VALE: 25 000 est. (20 000 infantry, 5 000 cavalry)
Doran notes that the Young Dragon had made Dorne’s numbers greater than they were when he wrote of the Conquest of Dorne. Dorne utilizes spearmen and mounted spearmen. When in front of Daenerys, Quentyn claims that Dorne has 50 000 spears and swords. This however is an inflated number. With above information, Dorne should have 28 000 ground troops, but I will round it down to 25 000 as Dorne is desert and also much smaller than North. Doran has 20 000 troops ready to march in the Winds, but he will not have deployed his whole strength while leaving Dorne completely unguarded, again pointing to ~25 000 troops.
TOTAL VALE: 25 000 est. (20 000 infantry, 5 000 cavalry)
- Ground troops: 244 500 (191 600 infantry, 52 900 cavalry)
- North: 29 500 (22 500 infantry, 7 000 cavalry)
- Riverlands: 20 000 (14 500 infantry, 5 500 cavalry)
- Westerlands: 35 000 (28 000 infantry, 7 000 cavalry)
- Crownlands: 20 000 (16 600 infantry, 3 400 cavalry)
- Stormlands: 25 000 (20 000 infantry, 5 000 cavalry)
- Reach: 65 000 (50 000 infantry, 15 000 cavalry)
- Vale: 25 000 (20 000 infantry, 5 000 cavalry)
- Dorne: 25 000 (20 000 infantry, 5 000 cavalry)
- Naval force: 1 180 ships, 152 500 men
- Crownlands: 260 ships, 42 250 men
- Reach: 220 ships, 35 750 men
- Westerlands: 200 ships, 32 500 men
- Iron Islands: 500 ships, 42 000 men
- TOTAL: 397 000 men
Notes on numbers and logistics
There is a significant inconsistency between terminology used and what is actually seen. Many of the forces discussed above are seen fielding significant portion of their military strength in one place. Logistically, that is not impossible: Romans fielded armies up to 100 000 strong for certain battles, and Romans from Middle Republic all the way to the end of Middle Byzantine period (so a period from 274 BC to 1070. AD) regularly fielded armies that numbered in tens of thousands. But this was made possible by strict structural organization, usually on the basis of 5 – 10 (Roman legions were organized on that basis: 10 men per decuria, 10 decurias per centuria, 5 centurias per cohors, 10 cohorts per legio, though exact numbers varied over time). Numbers in Byzantine army of Middle period were also highly standardized. This was a practical necessity – logistics depend on calculations, and these were done by officers of rudimentary literacy and numeracy. Large forces absolutely depended on this standardized, formalized organization to facilitate logistical supply they required to survive.
Figures for Roman (and Byzantine) armies can thus be divided into three categories: official establishments, censuses and guesses. Roman armies had highly standardized official establishments, but actual numbers could be – very slightly – lower or higher (due to losses, corrupt officials and such). In AD 285., Roman army had 35 legions. From this would follow number of 385 000 men (35 * 5 500 * 2, due to auxilliaries), while census reports 389 704 men. Byzantine armies are similarly structured: in AD 840., army was structured in tourmai of 5 000 men each, droungoi of 1 000 men each, banda of 200 men each, kentarchiai of 100 men each and kountobernia of 10 men each. Because of this, number of 250 000 soldiers of official establishment in 1025. is far from impossible; highly formalized and organized structure would also allow the Empire of the time to easly field two field armies of 40 000 men each.
Army can function with units of widely varying sizes only if it is a) very small, b) loosely organized or c) supplied with expert record-keepers. Feudal society would not have option c) in sufficient numbers to facilitate mass deployments. As such, armies had to be either very small or very loosely organized – latter would allow massive total establishment, but field armies would still be very small due to inability of supplying them. Medieval armies were often numbered in tens or hundreds, more rarely thousands, of men. Anglo-Saxon military system (fryd), introduced cca 600., was extremely organized and efficient for its time, only surpassed by Roman (Byzantine) themata and Frankish military system (both inheritors of ancient Roman military tradition). Yet it could only field very small forces: according to definition in King Ine’s law code, “We use the term “thieves” if the number of men does not exceed seven, “band of marauders” [or “war-band”] for a number between seven and thirty-five. Anything beyond this is an “army” [here]”. As it may be known, 35 men is slightly fewer than 35 000. In the late eighth century the æþeling (prince) Cyneherd considered his army of eighty-four men sufficiently large to attempt to seize the throne of Wessex. In 1028., Hugh V of Luisignan fields an “army” of 43 horsemen to win a castle and some land.
Yet, as can be seen, Westerosi armies routinely deploy tens of thousands of men in the field. This mirrors the situation of Wars of the Roses – which were fought in 15th century, well after the appearance of standing military in late 14th century. This de-feudalization was signalized by the indenture system of Edward I., which formalized retainer system by forming contracts of service. These contracts laid down precisely the size and the composition of the force, rates of pay, place of assembly, length of service and obligations. Because of these, barons, lords paramount and kings could plan for the organization, deployment and supply of their forces. But such an army was not feudal force: rather, it was a professional army. And this shows: at Agincourt in 1415., English field 6 000 – 9 000 trops, while the French field 14 000 – 15 000 professional soldiers and some 10 000 armed servants (so cca 25 000) at most; more likely number is 12 000 – 15 000 French soldiers in total. French defeat was enough to cripple military capability of France, suggesting that the force fielded was the bulk of the military power of the kingdom (not necessarily France as such, since factional divisions meant the king could not access full power of the kingdom). This is way beyond what purely feudal military systems could field as a coherent field army, even if total number of forces raised by feudal levy could far exceed these numbers. Kingdom of Hungary could easily field 40 000 soldiers in 1491. while Matthias Corvinus’ military organization was still in place, yet it managed to collect barely 28 000 troops of uncertain quality for crucial battle of Mohacs.
Logistics indeed feature prominently in A Song of Ice and Fire. An army of 12 000 is enough to eat the countryside of Winterfell clean. Tywin turns logistics to his advantage by sitting in Harrenhall and plundering the Riverlands, feeding his army on his enemies’ harvests. By this he meant to cause Robb to fight at Harrenhall. On the other hand, Edmure allows smallfolk inside his castle, despite the logistical strain that would cause. Northern army at least also has camp followers, who should be equal in number to fighting troops. It also brings herds of sheep, goats and scrawny cattle with it. Neither of these things was unknown in medieval times, but they both serve to slow the army down. Need to find pasture for the cattle also means that army is not capable of campaigning during the winter. Renly manages to field a host of 80 000, but that is a slow march along an easy supply route.
Communication is extremely quick however, as it relies primarily on magical ravens, not on couriers (actual ravens would have torn apart the message in trying to read it – they are too smart and too curious to make good messangers. That is why pigeons were used historically, being only a little smarter than average EU MP).
Sieges in Middle Ages could last for months or years. Yet feudal levies could only be in the field for a few months at most, and would have to be released home to plant crops or else gather them. This by itself clearly shows that warfare is not a seasonal occupation restricted to summer months, which it would have been if peasant levy was a significant way of providing troops (even accounting for screwed-up Westerosi seasons, we know that there are multiple harvests each ten-year summer, meaning that elongating the summer will not have prolonged actual campaigning season as crops presumably grow at the same rate). Such was the case with Greek hoplites – ancient Greek logistics were utter garbage, not because Greeks were idiots – though one could say that large number of personal servants hoplites took on campaign is indicative of widespread stupidity – but because hoplite warfare consisted of walking around, eating enemy’s crops and bashing the other bunch of hoplites, all done exclusively during summer months (more on Greek hoplite logistics can be read here and here). When enemy food stores ran out, invading hoplites simply went home. As such, campaigns were never fought during winter. But in late Middle Ages, sieges and general warfare alike were done all-year-round. Battle of Towtown in 1461. was fought in a snowstorm, yet it involved tens of thousands of troops – something only a professional army could achieve. In Eastern Europe, Arab siege of Constantinople began in 717., and continued into 718. – including throughout the winter. This again was a professional army. Westerosi armies do not have winter supply issues during sieges due to Planetos’ screwy ten-year-seasons, but they are modelled on armies which were perfectly capable of fighting in a (normal) winter. And indeed winter warfare is not impossible: there are references of northern troops going off to fight a war in winter – with explicit purpose of reducing the number of mouths that needed to be fed. In series proper, Stannis marches against Winterfell well after snows start falling, and to the south, neither the Ironborn, Tyrells, Lannisters, Tullys or the Golden Company think twice about fighting a war at the onset of winter.
Further, even professional feudal troops – such as feudal system had them (e.g. knights) – were not a standing army. They were “on retainer”, obliged to serve for a certain number of days per year (William the Conqueror required 40 days). This retainer system would have sharply limited not only the size of forces fielded, but also the distances these armies could march. Westerosi armies are routinely deployed across the whole continent, and travelling from Winterfell to King’s Landing takes multiple months. This is the area that is the size of Roman Empire at the very least; feudal armies would never have been able to fight anything other than local conflicts.
Lastly, Westerosi armies are both capable and willing of widespread destruction. This again is something that is only really seen in conflicts between professional armies: be it Hundred Years War, Wars of the Roses, Ottoman Wars in Western and Central Europe, or else wars involving Byzantine Empire and various Caliphates in the Eastern Europe.