The Size of Medieval Armies (A Complete guide)

When it comes to the size of Medieval armies than most of us immediately think about the armies that are presented by Hollywood in different movies. But while the army sizes in these movies often go into the hundreds of thousands the real medieval armies were much smaller.

In the following, I would like to present the sizes that armies could have during the Early Middle Ages, the High Middle Ages, and the Late Middle Ages by giving several examples of famous battles and the size of the armies that fought in these battles.

While Carolingian armies during the Early Middle Ages (500-1000) could consist of up to 10,000-20,000 men, the army that left Europe during the first crusade consisted of 30,000-35,000 men (5,000 of them mounted knights) and was considered one of the largest armies of the High Middle Ages (1000-1250). During the Late Middle Ages (1250-1500) the size of the armies would shrink.

Let`s find out more.

The size of armies during the Early Middle Ages (500-1000)

Please note that all the numbers I give are the maximum sizes that armies during the period would have. There were of course also much smaller armies for example during smaller conflicts or other events that did not justify the costs connected to field a large army.

And when we are talking about the size of armies during the Early Middle Ages then the first thing we have to remember is that not every man who was liable for military service would also participate in a campaign. You can find more information about that and the difference between the general levy, the expeditionary levy, and the household militaries, in my article here where I talk about the organization of Early medieval armies.

So during the Early Middle Ages (500-1000), the Carolingian kings could draw from a total military potential of 30,000-40,000 men. Each of these men would have to provide his own weapons and armor in case he was called in for participating in a war. That led to an army that varied in the extent to which the warriors were armored, more on that here.

But not all of these 30,000-40,000 men who were in theory liable for military service were simultaneously enlisted. Even during large-scale wars, the Carolingian armies did only consist of 10,000-20,000 men.

And in case the war was an offensive war then only men from the expeditionary levy and the household militaries of the king as well as secular and ecclesiastical magnates were drafted. The reason for that can once again be found in the different levels of wealth and equipment the men in the different levies had to have. You can find out more about the minimum level of wealth necessary for being a part of the expeditionary levy in my article here.

So now one might ask how we know about these numbers.

How do we know the size of early medieval armies

While the exact size of the Carolingian armies is unclear we can get a rough estimate from the structuring of the Regnum Francorum, the kingdom of the Franks.

The kingdom of the Franks was divided into roughly 2,000 administrative units of land ownership. The owner of each of these units could hand smaller parcels of land within his unit down to his followers but was also obliged to contribute a certain number of warriors to the king`s army.

The number but also the equipment with which the warriors had to show up depended on the size (and wealth) of the administrative unit, more on that here. So if we assume that each of these units had to contribute an average of 20 armored men – we know that some of the larger land units like the one governed by the bishop of Cologne had to send 100 mounted men – then we already have our number of up to 40,000 men.

These numbers are also supported by accounts that we have of certain battles. Do you want more information about how field battles were fought during the Middle Ages and how they differed from the battles shown in movies? Then I would like to recommend you my article here.

But back to how the accounts of battles confirm the numbers presented.

In 872 king Louis the German sent his son and an army (the exact size is unknown) on a campaign that would lead them over the river Danube. To cross the river the army had to set up a temporary bridge. And when the main army advanced against the enemy, bishop Emrich of Regensburg and a part of the army were left behind to secure the bridge.

During the night the bishop and his force were ambushed. And while bishop Emrich of Regensburg could escape with a few of his men, roughly 6,000 of his soldiers were killed.

So even if you grant that contemporary source some inaccuracy regarding the number of killed men it still seems like the rear guard that was left behind to secure the bridge was several thousand men strong. So in that context, it seems quite realistic that the armies the Carolingian kings assembled for large campaigns could count between 10,000 and 20,000 men.

But let`s now leave the Early Middle Ages and look towards the High Middle Ages, a period that most of us connect to the term Middle Ages. Here you can find my article with more information on the 3 different periods of the Middle Ages as well as an overview of important events and persons during each of these periods.

The size of armies during the High Middle Ages (1000-1250)

Since the Crusades are probably the best known military conflicts of the High Middle Ages I would like to present you two battles – one larger and one smaller battle – that were fought during the crusades.

But let`s first talk about the size of the army (or rather the several different armies) that left Europe during the first crusade (1096-1099).

The size of the Christian army that left Europe during the First Crusade

First, it is important to note that the troops that left Europe during the First Crusade were not organized in one army but into several armies that came from different parts of Europe. While one of the armies started its march in France, others came from different parts of Italy, Sicily, or the Holy Roman Empire.

Do you wonder why it was called the Holy Roman Empire (even though it had nothing to do with the ancient Romans)? Here you can find the answer!

But for the sake of better clarity, I will refer to these armies as one army since they had a common goal.

The army that left Europe and was able to conquer Jerusalem during the first crusade (1096-1099) was one of the largest armies of the High Middle Ages and consisted of a total of 30,000-35,000 men, 5,000 of which were mounted knights.

When the Christian army conquered Jerusalem their numbers had already dropped from the 30,000-35,000 men from the start of the first crusade to 12,000 men. That loss can be explained by desertions, losses, but also the troops that were left behind as garrisons of conquered strongholds along the way to Jerusalem.

But while that is the general number of soldiers that left Europe during the First Crusade we also have to look at two battles in the Holy Land to get a better idea of how different the size of medieval armies could be depending on the circumstances.

The battle of Hattin – an engagement of two large armies during the High Middle Ages

The battle of Hattin was fought in 1187 between the army of the kingdom of Jerusalem and the army of the Ayyubid sultan Saladin. For more information on Saladin, the Muslim expansion during the Middle Ages, and the 4 major Muslim caliphates of the Middle Ages you can check out my article here.

In the battle of Hattin on July 4th, 1187 the 30,000-40,000 men strong army of the Ayyubid sultan Saladin defeated the army of the Crusader states that consisted of 1,200 mounted knights and roughly 15,000 men on foot.

Needless to say that that kind of battle was one of the larger ones. Do you wonder how medieval battles were fought? You can find the answer in my article here.

But let`s compare that to one of the smaller battles that were fought in the Holy Land.

The battle of Ramla 1101 – a battle between two smaller armies

One of the smaller battles fought during the crusades was the battle of Ramla in 1101. That battle was fought between the kingdom of Jerusalem and the Fatimids of Egypt. Here you can find my article with more information on the Fatimids and the other 3 major caliphates of the Middle Ages.

During the battle of Ramla in 1101, an army of the kingdom of Jerusalem which consisted of 260 mounted knights and 900 men on foot defeated a Fatimid army that was made up of 3,000-5,000 men.

So now ft he looked at a smaller army as well as a larger army that fought during the crusades. And we also looked at the army that left Europe during the first crusade, one of the largest armies of the High Middle Ages.

Let`s now turn to the last period of the Middle Ages. By the way, in case you wonder about which events were used to differentiate between the Early, High, and Late Middle Ages you might want to check out my article here.

The size of armies during the Late Middle Ages (1250-1500)

Now we talked about the army sizes in both the Early and the High Middle Ages. And looking at the numbers of the large armies – the Carolingian armies consisting of up to 10,000-20,000 men and the army that left Europe during the First Crusade consisting of 30,000-35,000 men – the logical conclusion would be that the sizes of armies during the Late Middle Ages would grow once more.

But that was generally not the case.

The armies that were fielded during the Late Middle Ages were not really that much larger (if at all) than the largest armies (10,000-20,000 men) that the Carolingians had fielded during the Early Middle Ages.

A good example of that is the war between Louis IX, the duke of Bavaria-Landshut, and Albert III, Margrave of Brandenburg.

By the way, the wedding that Louis IX, also known as Louis the Rich, organized for his son in 1475 is still celebrated every fourth year in Landshut. If you should find yourself in the area and you are interested in one of the most authentic medieval pageants worldwide then I would highly recommend you to visit. Here you can find more information as well as pictures of the pageant.

In 1462 Louis IX, Duke of Bavaria-Landshut fielded an army of 20,000 men against his enemy Albert III, Margrave of Brandenburg.

Another famous battle of the Late Middle Ages is the battle of Agincourt.

During the battle of Agincourt in 1415, an English army of roughly 6,000 men (about 5/6 archers, the rest dismounted men-at-arms) was able to defeat a French army of up to 24,000 men (10,000 men-at-arms, 5,000 archers, and another 10,000 armed servants who each accompanied a man-at-arms).

But not only did the size of armies change during the Late Middle Ages. Their composition changed too.

How did the composition of Medieval armies change over time

The armies of the Early and High Middle Ages were mostly made up of vassals who owed military service to their lord. In return that lord owed military service to his lord, and one of the lords would eventually owe military service to the king (= the feudal system).

During the Late Middle Ages (1250-1500) the number of mercenaries in the armies grew while the number of vassals and noble knights fulfilling their obligation of military service to their lord dwindled.

That development would go on for centuries. But that development and why the armies of mercenaries were eventually replaced by armies of citizens (that are still used today) is a story for another time.

If you want to learn more about medieval battles then you might want to check out my article here where I talk about how long medieval battles lasted.

Take care of yourself because you deserve it. You really do.

Until next time

Yours truly

Luke Reitzer


David S. Bachrach: Warfare in Tenth-Century Germany (Woodbridge 2012).

Malte Prietzel: Krieg im Mittelalter (Darmstadt 2006).

Karl Heinz Zuber, Hans Holzbauer (Hrsg.): bsv Geschichte 2. Vom frühen Mittelalter bis zum Westfälischen Frieden (München 1983).