[inglor_cz]

If you want to see some really brutal wars, you need to go back from the Middle Ages into Antiquity.

The ancient empires were able to gather armies much larger than any medieval king could, and, at the same time, people had few qualms about genocide. There weren't even religious reasons not to commit one, much less any chivalry codes etc.

The Romans in particular had the principle of "aries murum attigit", which meant that a city had time to surrender until the first battering ram touched its walls. After that, the captives would be put to the sword.