The exception was in Northern Greece, where large flat areas of grassland made cavalry much more practical. Eventually, encounters with Persian cavalry led the Greeks to create their own cavalry arm, the Hippeis, composed mostly of upper-class citizens who could afford to maintain a horse. While cavalry played an increasingly greater part in Greek warfare, its roles were generally restricted to scouting, skirmishing and pursuit. However, by the end of the Peloponnesian War, heavy cavalry charges had started to play an increasingly important part in Ancient Greek warfare, with the Battle of Delium showing how their intervention could turn the tide of a battle. The city-state of Thebes was particularly famous for its cavalry, with the famed Theban commander Epaminondas using his heavy horse to great effect both at Leuctra as well as Mantineia to rout the Spartan cavalry, and in the process disrupting the legendary Spartan phalanx as well, helping his own hoplites win the battle.