Greek strategy changed considerably at Salamis; whereas Leonidas and his Spartan force of 300 men dominated Thermopylae, Salamis was predominately directed by Themistocles and the Athenian navy. Thucydides describes Themistocles’ “ability and intelligence” in his History of the Peloponnesian War, attributes that were used to their full advantage at Salamis. In the lead up to Salamis Themistocles acted as the strategic figurehead, insisting, as Herodotus describes, that the Greek force must continue fighting and that it must be a naval battle as the Spartans’ idea of building a wall to seal off the Isthmus of Corinth would fail, with the Persians breaking through and defeating them as they did at Thermopylae. Herodotus’ account can be called into question, as it is known that he relied heavily on young soldiers as his informants, who would not have been aware of exactly what was said at the meetings of the generals, however, his account is verified by Diodorus Siculus who reported the same. His argumentative and persuasive skills allowed Themistocles to get his motions carried through; Plutarch records the argument between Themistocles and Eurybiades about the Spartan vote “to build a wall across the Isthmus” (Diodorus Siculus), as Eurybiades saying “You know, Themistocles, at the games they thrash anybody who starts before the signal” to which Themistocles replied, “Yes, but they do not crown anybody who gets left at the post”. Although it is unlikely that Plutarch will have known the exact words of the conversation and furthermore, it is doubtful that the conversation was so snappy and witty, it does demonstrate Themistocles’ persuasive skills and how they allowed him to justify and follow through with his ideas and actions. Plutarch further highlights Themistocles’ strategic ability when he states, “Themistocles appears to have chosen the time for the battle as judiciously as he had the place”. By this, Plutarch is referring to the fact that Themistocles did not let the Greek triremes engage with the Persian fleet head on until a particular time of day when the wind was right; the wind was of no disadvantage to the Greek triremes as they had smaller ships that laid low in the water, but the Persian fleet could not cope with the wind as they had “high decks and towering sterns” (Plutarch.Them.14). Despite the fact Themistocles allowed Eurybiades to command the Greek fleet, in order to keep the Greek poleis together, it was Themistocles who all eyes were drawn to at the next Olympic Games in Greece, rather than the competitors or Eurybiades. Furthermore, Plutarch records that the Spartans “gave Eurybiades a prize for valour, but Themistocles one for wisdom…they also presented him with the finest chariot in the city”. This change in strategy, dominance of the Athenians, as opposed to the Spartans, and the leadership of Themistocles at Salamis, is likely to have contributed to it being a turning point in Xerxes’ invasion as it led to “the greatest fleet in the memory of man [being] conquered… by a small number of ships” (Cornelius Nepos. Them. 5).
Thermopylae can be seen as the turning point in Xerxes’ campaign because, after the Battle, many more Greek states united together to fight against the Persians in an attempt to emulate Sparta’s valour in their fighting. Herodotus’ description of the Spartans fighting with “bare hands” and similar, at Thermopylae will have spread across Greece, encouraging many to put together troops and fight in a similar way in future battles. Despite their failure, Leonidas and his small force deserve an honoured place among military heroes; their rear-guard action prevented the Persians overtaking the rest of the retreating forces. Thermopylae was not a total failure. The invading army had been bloodied badly, if Herodotus is to be believed, and it must have had some effect on Persian morale. The Battle's influence on the Greeks was indisputable. When the war was over, the Greeks established holidays commemorating Thermopylae and erected memorials over the battlefield. One memorial celebrated Leonidas and his 300 men: “Go tell the Spartans, stranger passing by that here, obeying their commands, we lie.” Thermopylae thus acquired a significance that transcended its tangible military impact. In the end, the Battle's value as a turning point in Xerxes’ invasion lay not in land gained or lost or in men killed or captured, but in inspiration. The Spartans and Thespians had taught Greece and the world an enduring lesson about courage in the face of impossible odds.
The Battle of Plataea was a turning point of Xerxes’ campaign in Greece as it was the final battle to take place, ending in the death of Mardonius and the subsequent retreat of his forces. Plataea was different to Thermopylae and Salamis as, again, tactics and leadership changed. Rather than inspirational leadership comparing with Themistocles at Plataea, both Greek and Persian leadership was weak. Arguably it was mere chance that the Greeks defeated the Persian army. Indeed, Mardonius felt that there was little to be gained from the expedition and so simply waited for the Greek alliance to fall apart. This stalemate continued for a considerable amount of time, as both sides were fortunate in having substantial supplies to keep them going for months; it could be argued that the only praiseworthy strategic tactic Mardonius initiated was to raid the Allies’ supplies, thus forcing the Greeks to adopt a change in tactics. However, hereafter the Battle came down to luck as the Persians pursued the retreating Greeks only to find that they had been inadvertently lured into being attacked on higher ground and so, despite the Persians outnumbering the Greeks, the topography provided a much larger advantage, this was not, however, due to any strategic ability of Pausanias but merely good fortune. It is evident that Mardonius was a poor commander as, once he was killed by Arimnestus, his troops immediately retreated. This suggests that they did not believe in the cause and were not inspired by their leader, as they were at no risk of losing liberty over the expedition and so used the event to flee rather than risk their lives for another man’s expansionist desires. Plataea is often cited as one of the best examples of Greek unity, and thus a turning point in Xerxes’ invasion, as approximately 23 states had taken an oath of comradeship to fight together until the barbarian invaders were destroyed; despite the threats to unity over the three weeks, it was a national alliance, however short-lived. Plutarch outlines the importance of Plataea as a turning point when he records that “all Greek states should meet at Plataea every year” and that “festival games should be held every four years”.
Overall, it could be suggested that Salamis was the key turning point of Xerxes’ invasion as, every battle before it, ended in defeat, whereas, every battle after it, resulted in victory. Furthermore, it ended the Persian strategy of combined naval and military operations and left the Persian army without a supply line. Salamis also weakened the allegiance of the Greeks in Asia Minor and paved the way for the revolt in 479 BC. According to Thucydides, Salamis saved the Peloponnese as “it prevented the Persians from sailing against the Peloponnese and destroying the cities one by one”. Thermopylae and Plataea, although extremely significant, were not as key as Salamis as turning points in Xerxes’ invasion.