How Large Were Medieval Armies?

Taking a general view of things, it seems that a common size for medieval armies was between 5,000 and 25,000 troops, with some of the largest formal organizations of armed forces numbering into the possible 500,000 to 600,000 troops in number.

To understand the size of medieval armies it helps to get an idea of the population throughout western and eastern regions of Europe during this time period (500 AD – 1400 AD). There was no real census conducted until the 18th century so the numbers vary from source to source. 

Russell estimates that between the years 500 and 1400 AD the total population of South, West, and Eastern Europe more than doubled from 27.5 million to 73.5 million right before the Black Death began in the 14th century, which quickly dropped a third of the population.(1)

It is helpful to consider that through most of the middle ages, 90 percent of this population was still involved in direct production of goods. This left only 10 percent of the population to the specialized classes, including everything from governing bodies of education to soldiers and mercenaries. 

During the crusades, one kingdom or municipality could usually summon armies numbering in the 10,000s. Though seldom in the same place at the same time, if all the allied forces were gathered the armies could have numbered in the 100,000s. 

In the Third Crusade, which took place at the end of the 12th century, the total number of European troops including Welsh, German, French, and Hungarian armies numbered 36,000 to 74,000. (5)

What Was The Largest Medieval Army?

One of the largest estimates of troop size comes from the Sui Dynasty in China. According to varying accounts and estimates, it is accepted that 600,000 to 1.1 million troops were mobilized in order to take over the Korean peninsula in the 7th century. (3)

In Europe, one one of the largest commonly accepted estimates of medieval troop size comes from historian Kuczynski, concerning the Battle of Grunwald, also known as the First Battle of Tannenberg. This enormous battle took place on the 15th of July in the year 1410 during the Polish-Lithuanian-Teutonic War. Kuczynski’s estimates put the Polish-Lithuanian at 39,000 and the Teutonic men numbered at 27,000. (2)

Even so, during the Hundred Years War, France was able to amass as many as 50,000 to 60,000 troops even though they were not all located in the same place. Logistics, strategy, and supply lines kept these large armies from grouping together in one place and time. 

While estimates of population size and army gatherings are often given in wide ranges, we can still assume some accuracy. When considering some of the largest forces in the medieval ages, the range can be quite large, even double the total mass of force. It is important to consider the many factors involved when combining varying accounts of armies joining forces.

How Big Were Medieval Mercenary Armies?

During the second half of the 14th century, Siena spent a relative fortune on what is known as free companies, bands of mercenaries that sold their services to the highest bidder. 

The White company is one of the most notable companies of this time. At the height of the White Company, they are assumed to have amassed 3,500 cavalry and 2,000 infantry.

Led by John Hawkwood, the White Company had great influence around Italy in the later half of the 14th century. Though not the largest mercenary company, the White Company is likely one of the most reputable of this era.

At the beginning of the middle ages, most armies were composed of loyal subjects bound by oath, duty, and necessity. As the middle ages continued to develop more complicated styles of warfare and strategy, a professional class of warriors and mercenaries soon took over the scene of military combat. Of course any peasant could be made to pick up a pitchfork. Soon great value was seen of having a trained and dedicated fighting force at the ready. 

What Was The Composition Of A Medieval Army?

Due to the rapid development of advanced warfare technology, the warring classes began to divide the labor of war into several different roles. Usually these specific roles were adopted by mercenaries or trained knights who made a career out of one particular style of combat.

Almost all armies contained some element of both cavalry and infantry. The ability to move swiftly across the battlefield helped in implementing strategies of outflanking, surprise attack, and even frontal assault. Of course the cavalry was limited by the number of horses available.

Archers became an increasing necessity in medieval warfare. The ability to put pressure on enemy infantry from a great distance was highly sought after. The English were known for their longbow-men. They continuously increased their ratio of archers to men-at-arms eventually reaching an astounding composition of 3 to 1. 

During the Diet of Worms, a conference held by the Holy Roman Empire in 1521, it was set forth that a force of 20,000 infantry and 4,000 cavalry. This force was maintained by a taxation or provision of cavalry or infantrymen by various territories. While this force served as a standing army of sorts for many years the initial purpose of the army was simply to safely escort the emperor to Rome where he would be crowned by the Pope (4).

Side note: If you are curious to learn more about the Holy Roman Empire, we have written up a nice comparison against the Roman Empire.

How Big Was A Medieval Military Unit?

Military units in medieval times were typically divided into three groups the vanguard, middle guard, and rearguard. Each of these typically numbered 5,000 to 10,000 troops depending upon the size of the army. The Swiss famously used wide and thick columns of soldiers known as square formations. Usually these formations ran 56 men wide and 20 men deep. (6)

One of the most famous mercenary companies, the White Company was not the largest of mercenary companies but arguably the most successful, some would say due to its size and maneuverability. In the year 1361, the Company boasted a force of 2,000 infantry and as many as 3,500 cavalry. Few armies claimed to have more cavalry than infantry due mainly to the expense of maintaining horses and trained riders. 

When looking at sizes of typical medieval military units, it is useful to consider the necessary inputs and possible outputs. Of course it is ideal to have had a large number of highly trained troops at the ready. Though, the larger the army, the more resources are needed to support their pay, training, and material necessities. 

It is also worth noting that the Bulgarian army maintained a heavy cavalry. Nearing 900 AD it became one of the most intimidating forces in Europe. Some estimates for the size of this cavalry near 12,000.


Accounts vary widely. Medieval scholars share a tendency to embellish the truth concerning crowd size as well as that of standing infantry and cavalry. Expert historians may come to some general consensus about the size of armies or crowds based on several factors and inputs including supply lines and tax base. Taking a general view of things, it seems that a common size for medieval armies was between 5,000 and 25,000 troops, with some of the largest formal organizations of armed forces numbering into the possible 500,000 to 600,000 troops in number.

Source Citations

  1. The information here is taken from Josiah C. Russell, “Population in Europe:, in Carlo M. Cipolla, ed., The Fontana Economic History of Europe, Vol. I: The Middle Ages, (Glasgow : Collins/Fontana, 1972), 25-71
  2. The high-end estimates by Polish historian Stefan Kuczyński of 39,000 Polish–Lithuanian and 27,000 Teutonic men[37] have been cited in Western literature as “commonly accepted”. The Battle of Grunwald, Battle of Žalgiris or First Battle of Tannenberg was fought on 15 July 1410 during the Polish–Lithuanian–Teutonic War. The alliance of the Crown of the Kingdom of Poland and the Grand Duchy of Lithuania, led respectively by King Władysław II Jagiełło (Jogaila) and Grand Duke Vytautas, decisively defeated
  3. Frederick W. Mote; Denis Twitchett (26 February 1988). The Cambridge History of China: Volume 7, The Ming Dynasty, 1368-1644
  4.  Thomas Robisheaux, Rural Society and the Search for Order in Early Modern Germany (2002), p. 177
  6. Miller, Douglas (1979). The Swiss at War 1300-1500. Osprey. p. 17. ISBN 0-85045-334-8.