Roughly in the 8th century of our era, wealthy people who owned horses thought that they could fight while mounted, using spears and swords. This was the era of Charlemagne. In their conquests, the Franks increasingly mounted horses to achieve offensive success as true cavalry, rather than just horse infantry. This is how the first knights appeared. One hundred years later, Charles the Bald called upon all men who could afford horses to respond to the call of war with weapons, to swiftly repel the constant and large-scale Viking invasions...