In 550BC the Spartans defeated Tegea, this was followed by Argos in 544BC. From 520-490BC under king Cleomenes Sparta was seen as the leader of the Peloponnese and the leader in Greek defence against Persia. In 490BC the Peloponnesian league was created with Sparta as the recognised leader. Despite all this, the Spartans never managed to get control over as much, or of the same areas of the Greek world that Athens did. The reasons for this are far from straight forward. The unique Greek mentality towards warfare, the superior Athenian navy, the mighty Persian Empire, basic geography, key individuals and natural disasters were all to play a part. Rather than simply naming Sparta the 'weaker' or less successful power, (the evidence itself disproves this as, if only for a short time, Sparta managed to crush Athens, installing the regime of the 'thirty tyrants' in 404BC) I believe that it was a combination of all of these factors that combined, in the long term, to work against Sparta.
Whilst the Peloponnesian League has been called "the most formidable alliance in Greece" Its creation in 490BC actually marks a reduction in Sparta's power over its Peloponnesian allies. …
