Feudalism, once more, was a system of local defense. The
knight must guard his small estate, the baron his barony, the count his county,
the duke his duchy. At the lord's bidding the vassal had to follow him to war,
either alone or with a certain number of men, according to the size of the
fief. But this assistance was limited. A vassal served only for a definite
period (varying from one month to three in the year), and then only within a
reasonable distance from the lands for which he did homage. These restrictions
made it difficult to conduct a lengthy campaign, or one far removed from the
vassal's fief, unless mercenary soldiers were employed.
THE FEUDAL ARMY
The feudal army, as a rule, consisted entirely of cavalry.
Such swiftly moving assailants as the Northmen and the Magyars could best be
dealt with by mounted men who could bring them to bay, compel them to fight,
and overwhelm them by the shock of the charge. In this way the foot soldiers of
Charlemagne's time came to be replaced by the mailed horsemen who for four
centuries or more dominated European battlefields.
