There are many possible answers regarding this topic but by following the sources we could analyze the possible number of troops that were fighting in a single battle during the medieval period.

Comparing the medieval period with the ancient period, we are to conclude that a lot of things have changed in the battlefield. In the ancient period the army was more professional and because of this, the force was bigger and stronger. Looking back at the medieval period, the army wasn’t so professional and this was one of the reasons why the medieval period had lower numbers in troops.

Which Armies Were the Largest?

First of all, this is really hard to answer because the numbers could always be exaggerated. Starting from the hundred years war France called up to 50 000 – 60 000 soldiers, even though they weren’t stationed into one place. There was a single unit with around 25 000. England had around 30 000 soldiers. If they clashed, the number would have been around 50 000 – 60 000 and this could escalate into a huge fight.

Also it’s worth mentioning the Holy Roman Empire, which had around 80 000 – 100 000 soldiers before the Third Crusade. This force could cause some serious damage if it was deployed in the east. There are also other worthy mentions but the number wouldn’t get higher

The Biggest Battle is Far East

Medieval China was a pretty serious war machine and if it was possible to clash with a European state at the time, which knew how the outcome could turn out. China was too busy fighting against its neighbors; therefore, causing some serious trouble given the numbers it possessed, we are simply going to assume that China was a force not to be messed with.

At the current time China had a population around 100 million people, which was a huge number for the medieval period. In 1363 the battle of Lake Poyang took place and this might have been the largest battle to ever take place in the medieval period that we know of.

It is believed that the amount of troops deployed in this fight was around 800 000. This is a massive number for this period and it sounds almost impossible. But considering that China had dense population at the time makes it almost possible for this battle to be true.

Even though the numbers could be a little exaggerated, even if it were to drop around 200 000, it would still be one of the biggest battles ever to take place.

There are other possible candidates regarding this topic such as the Sui Dynasty mobilization of troops. By the sources it’s believed that this dynasty recruited around 600 000 to 1.1 million troops for the campaign to take over the territory of Korea.

Finally, feel free to comment regarding this topic because there is always a possible dispute over the numbers and facts, so you are allowed to theorize.

Sources:

Frederick W. Mote; Denis Twitchett (26 February 1988). The Cambridge History of China: Volume 7, The Ming Dynasty, 1368-1644