The Greeks sure seem to like the number 300. The 300 Spartans (and their 7,000 allies) at Thermopylae, the 300 Theban Sacred Band, and the little-known battle of the 300 Champions, fought very early in Greek history. Before Persia was a grave threat, actually while Cyrus the Great was building Persia into an ancient superpower, the Greeks quite often fought amongst themselves. Greek shared culture did exist and this thin unity would save the Greeks from Xerxes later, but the link was thin enough for countless Greek cities to be ruthlessly sacked through a variety of Greek City-State wars.Read it all here. You won't be disappointed!
One such war was between the Spartans and the people of Argos (known as Argives, not Argonauts who were a band of mythical heroes) over the coastal town of Thyrea that lay between the two city-states. make no mistake, the Argives were outstandingly fierce soldiers, especially so during their early history. Around this time Argos directly competed with Sparta for dominance of the Peloponnese and competed well. When the Spartans took over the fertile plains of the Argive-allied Thyrea, the Argive army confidently marched out in force.