Roman legion
Equites (cavalry): The cavalry was originally the most prestigious unit, where wealthy young Roman men displayed their skill and prowess, laying the foundation for an eventual political career. In a total of circa 3000 men, (plus the velites that normally enlarged the number to about 4200), the legion had only around 300 horsemen, divided into 10 units (turmae) of 30 men. These men were commanded by decurions. In addition to heavy cavalry, there would be the light cavalry. In battle, they were used to disrupt and outflank enemy infantry formations and to fight off enemy cavalry. In the latter type of engagement they would often (though not always) dismount some or all of the horsemen to fight a stationary battle on foot, an unusual tactic for the time, but one that offered significant advantages in stability and agility in a time before stirrups.