Another data point for the definition of Empire being control of foreign policy. H.H. Scullard writes on Rome's run-in with Sparta:

But Flaminius would not go as far as his [Greek] allies desired; as with Phillip [of Macedon], he wished to cripple, but not destroy. Once again it was the Romans and not the allies who dictated terms, which included the surrender by Nabis of Argos and other towns and of his fleet, an indemnity, and the renouncing of the right to make war or alliances.

When Germany established a colony in New Guinea in the 1880s Queensland raised up militia and prepared to go and kick the Germans out. The Colonial Office was not happy, and told the Colony of Queensland to drop any thoughts of military action against the German outpost. Britain was concerned it would precipitate war in Europe.

It is interesting to note that Australia didn't bother ratifying the Statute of Westminster until 1942 after the GAPF had been switched from the UK to the US.

The Department of External Affairs was established in 1935 when it was split out of the Prime Minister's department. Prior to that the Prime Minister had usually dealt directly with the Dominions Office and it was not until 1974 that the Australian High Commissioner in London reported to the foreign affairs department rather than directly to the Prime Minister.

Joan Beaumont writes:

The department's role in these pre-1939 years was so limited that it was scarcely recognisable as a modern foreign office.

Quite late in Australian history.

Old rusty nails via Husard's flickr photostream

Sparta was quite a backward state. At the beginning of the Peloponnesian War their monetary system was based on iron rods; not gold or other precious coins - basically they traded rusty nails as currency.

Since the Greeks were always loose confederations of city-states that formed alliances largely based upon their political systems; Athenian democracy vs Spartan Oligarchy or Tyranny, statecraft was a valuable tool. Wealth entered into that and this area Athens had it all over Sparta.

Paying for an extended war with rusty nails probably does not inspire confidence in oligarchic allies.

Cunning Realist writes on trauma cocktails which effectively make a nation accept anything; breaking down individual and social norms such that extremes become accepted as the new norm.

One of the interesting aspects of the Peloponnesian War was that the normal method of determining conflict between Greek city-states, hoplite battle, was replaced with political and ethnic genocide. Asymmetric warfare ruined the wealth, morality and power of Greece such that the Macedonians and then the Romans replaced them as the centre of Mediterranean power.

The shocks of two generations of continuous warfare, asymmetry, ethnic genocide, political turbulence, political genocide (people were wiped out for being oligarchic or democratic in their politics), plus the plague in Athens all led to a Greek trauma cocktail where plunder and genocide became the norm. It destroyed the power of Athens and Sparta; making them easy prey for Phillip of Macedonia and later the foreign policy politics of Rome's Scipio Africanus.

The A on that map is Thermopylae where the famous last stand of the Spartans and Plateans occurred. The sea has moved back from the cliffs and is now far out into the plains due to 1600 years of erosion and weathering. Thermopylae is seen as the battle that saved the West from Persia and cemented the Spartans as the great warrior society of ancient times. But is it?

Thermopylae is certainly dramatic. The Spartans knew they would be out-numbered and in their highly militaristic state controlled society where a warrior's death in battle was romanticized as the highest form of civic good has resonated in narrative history and story telling since. But with a rational eye was it a pivotal battle. The answer has to be no.

The Spartans were bizarrely superstitious even for their semi-animistic times. As a consequence it was the Athenians and other city-states that often bore the brunt of the Persian intrusions into Greece. Other than the battle of Platea where the Spartans bore the brunt of Persian forces, the other battles were victories by the democratic city-state of Athens.

Prior to Thermopylae the Persians had brought an army over to Macedonia and Greece. The Athenians met them in set battle at Marathon. The Persians were routed. At the time Athens had just thrown off the irons of Tyranny and Aristocracy and was a newly minted form of self-government in democracy. Common today, but not then. The other Greek states watched to see if this new form of political and social organization would be able to withstand the pressures of war. It could. As Marathon showed.

The real reason that the Athenians won at Marathon was that their military weapons and the social organization of the Phalanx was superior to the Persian arms, armaments and battle formations. The armor of the Phalanx was bronze and the main weapon was the shield and spear. Coupled with the tightly disciplined formation of the Phalanx the wicker armor and charges of the Persians were no match.

Thermopylae and Platea showed again that despite the superior cavalry forces of the Persians, which were well used, once it came to set battle the Phalanx formation of the Spartans and Athenians was superior to the armor, weaponry and formations of the Persians.

When Xerces tried to force his way through to Attica and the Peloponnese he successfully got past the bottle neck of Thermopylae despite the valiant stand by the Spartans and Plateans. The Persian invading force - while large in numbers of land forces - was also an amphibious force of triremes. Like today, naval power in the Mediterranean allowed for power projection over a wide area. It was Athens naval empire that allowed it to survive the 30 year war with Sparta for such a long time after the Greeks had defeated the Persians.

The battle of Salamis was largely an expression of Athenian naval power. They soundly defeated the Persian fleet, even embarrassing the Phoenicians who were the Persian naval elite. Apparently Xerces was watching from a nearby hill as the battle unfolded. It was after this naval battle that he gave up personally seeing the Greeks brought to their knees and headed back to the Persian empire to bring the rebelling Babylonians back into line.

So like Marathon which ended the first invasion force, it was Salamis which blunted the Persian advance into Greece. The remaining Persian land forces were later defeated at Platea but it was the Athenians again who stopped the Persians.

Thermopylae is dramatic and has romance written all over it for the selflessness death of the Spartans, but in terms of being pivotal it was not. Marathon and Salamis largely established what was to be the Athenian empire through Greece and Ionia. It was also the rise of Athens that would lead them to ongoing conflict with Sparta during the Pelopponesian War as the two Greek powers fought what was a civil war for control of Greece.