uate to stop a
rush of horsemen; when the latter threatened to intervene, they had to
run for safety to the squares of pikemen, whom they assisted in turn by
keeping the cavalry beyond pistol range. Hence the horsemen had to fall
back upon more powerful guns, and these, being slow and requiring more
train, could be most economically protected by infantry (see also
ARTILLERY).

17th-century progress.

Thus about the close of the 16th century western armies differentiated
themselves out into the still existing three types--cavalry, artillery
and infantry. Moreover, each type was subdivided, the cavalry becoming
heavy, medium and dragoons. At this period there was nothing to disturb
the equilibrium of two contending forces except the characters of their
respective leaders. The mercenary element had triumphed everywhere over
the feudal levies. The moral qualities of all were on the same
indifferent level, and battles in the open followed one recognized
course. Neither army being able to outmarch the other, both drew up
masses of pikes in parallel lines. The musketeers covered the deployment
of the heavy guns on either side, the cavalry drew up on the wings and a
strictly parallel fight ensued, for in the absence of a common cause for
which men were willing to die, plunder was the ruling motive, and all
control and discipline melted in the excitement of the contest.

It is to the growth of Protestantism that cavalry owes its next great
forward leap. To sweep the battlefield, it was absolutely essential that
men should be ready to subordinate selfish considerations to the triumph
of their cause. The Roman Catholicism of the day gave many loopholes for
the evasion of clear duty, but from these the reformed faith was free,
and it is to the reawakened sense of duty that Gustavus Adolphus
appealed. This alone rendered combination amongst his subordinate
leaders possible, and on this power of combination all his victories
depended. Other cavalry soldiers, once let loose in the charge, could
never be trusted to return to the field, the prospective plunder of the
enemy's baggage being too strong a temptation; but the king's men could
be depended on, and once brought back in formed bodies, they rode over
the enemy's skirmishers and captured his batteries. Then the equilibrium
of force was destroyed, and all arms combined made short work of the
opposing infantry alone (Breitenfeld, 1631). But the Swedish king
perished with his