After the failure of the Ionian revolt the Hellenic states turned towards the seemingly inevitable Persian invasion. Herodotus states that the Greeks were expecting another invasion by the Persians and the whole of Persia was preparing for war (7.1-2). In this way, Herodotus sets up the Ionian revolt as a precursor to the Greco-Persian Wars. Darius does send generals against Athens after the Ionian revolt. Along the way the Persians are able to subdue Carystus, Naxos, and parts of Eretria (6.95-100). This indicates that Greece was not the only area the Persians were looking to at the time. The Persians then decide to land in Attica at Marathon and the Athenians resolve to meet them (6.109). The Persians are then surprisingly defeated by the Greeks and while they do sail around to Athens decide not to attack it (6.110-6.118). The invasion is then abandoned and the Persian fleet sails back towards Persia. According to Herodotus Darius spends the next few years preparing for another Greek invasion. However his death ultimately prevents him from undertaking the endeavour. Another excursion against the Greeks is then picked up by Darius’ successor Xerxes. While Herodotus places Darius’ motives for a Greek excursion solely on revenge there is not such a clear cut reason for why Xerxes decided to invade Greece in 480 BCE.  Ancient sources give unsatisfying motives and place blame on either an individual or supernatural causes. For instance Herodotus blames both the aspirations of Xerxes’ cousin Mardonius and a series of dreams as motives for Xerxes taking up the expedition. Diodorus Siculus, mirroring Herodotus, leaves out the dreams but also blames Xerxes’ invasion on Mardonius’ self-interests. Looking past individual gain and the supernatural, the historians do however offer insight into what the potential motives for Xerxes’ invasion of Greece may have been. These include hostility predating the Ionian revolt, the need for revenge on mainland Greece, peer pressure from council members, pro-Persian feelings in mainland Greece, and a persistence of Persia’s expansionist policy (as was seen under Darius).
Hostility between Persia and Athens
Herodotus emphasizes the fact that there was animosity between Athens and Persia after Athens sent aid to the Ionians during their revolt. There is evidence, however, suggesting that this hostility was apparent before the revolt. Herodotus notes Athens asking Persia for help in the early sixth century BCE against Sparta. The Persians ask the Athenian envoys that had been sent to give earth and water in order to make an alliance and the Athenian envoys comply. Athens later becomes apprehensive to an alliance when they realise what the gifts mean and later reprimand the envoys (5.73). Misunderstandings are further fueled between Athens and Persia when Athens refuses Persia’s requests to reinstate the tyrant Hippias (5.96). This according to Herodotus was the cause for the open hostility to Persia (5.96). This is logical as at this point as the Athenians had technically submitted to the Persians and then had openly rejected Persian leadership. This submission and then rejection of Persian rule may have been a deciding factor in Xerxes’ reason for the Greek expedition.
Need for Revenge on Athens
The notion of revenge as a main motive behind the second invasion of Greece is one repeated throughout Herodotus’ narrative. After the Athenians had sent aid to the Ionian revolt Herodotus states that Darius asked who the Athenians were and had one of his slaves remind him of the Athenians every day before he sits down to dinner (5.106). Thus begins Darius’ vengeance against the Athenians. The notion becomes dubious however, when one remembers that Athens and Persia had been on bad terms before they had sent the ships to the Ionian revolt as a result of the Athenians refusing to reinstate Hippias as a tyrant (5.90-97). Thus Darius would have likely known who the Athenians were before they had sent aid to the Ionians. This notion of revenge is repeated with Xerxes, although mainland Greece would have done little to upset him at the time. Herodotus has both Mardonius and Xerxes state revenge as a motive for attacking Greece. Xerxes, when explaining the desire to conquer Europe, states (according to Herodotus) “(I) will not rest until I have taken Athens and burnt it to the ground” (7.8.b). Xerxes then goes on to list his anger as a by-product of the Athenians sending help to the Ionians and “the way they treated” Persian troops on Greek soil. While Xerxes being angry as a result of this is logical his anger at the treatment of his troops stands out as absurd. It must have been expected by Xerxes that an expedition would have been met with some resistance, despite the pro-Persian feelings present. It should be noted that Xerxes also needed some persuasion to take revenge on Greece. Herodotus claims that Xerxes was “not at all interested in invading Greece” but Mardonius, constantly talking to him about the Athenians, appears to persuade him to undertake a campaign. However, Xerxes has continuous second thoughts about undertaking the campaign. He is only ultimately persuaded after a series of dreams in which a phantom tells Xerxes to undertake the expedition. Xerxes’ reluctance to undertake a campaign against Greece and his apparent forgetfulness of the Athenians makes the motive of revenge dubious.
There is archaeological proof in Athens that suggests the Persians had attempted to completely destroy Athens. This is found in temples where religious items which had been destroyed were left on display. Often the Persians would have needed a special/specific reason to burn religious areas of an area they wished to subject.  More often the Persians kept other areas’ religious temples intact. This is seen in Herodotus when the Persian fleet reaches Delos. The Delians, scared, flee to the island of Tenos. The Persian general Datis does not anchor at Delos however stating that he had “enough sense” not to harm the island of Apollo and Artemis (6.98). This proves that the Persians mostly respected the religious areas of other nations. While the burning of religious items does serve as proof that the Persians did burn Athens it does not necessarily direct towards a revenge motive behind their actions. While it no doubt would have served that purpose (if that was the purpose) it would have also sent a strong message to other Greek factions still fighting against the Persians. The notion of revenge for the Ionian revolt is also skeptical as the Persians had already sacked the city of Miletus and enslaved its inhabitants for its leading role in the revolt and the burning of Sardis. As the Persians mopped up the remnants of the revolt no other city is mentioned as being treated so brutally. The Persians in Herodotus also do not seem as distracted by other factions that had helped out with the revolt (such as Caria). This suggests that the attack on Athens was a means to something else.
Peer Pressure from Council Members
Both Herodotus and Diodorus Siculus give large amounts of credit to the persuasion of Xerxes by Mardonius as cause for the invasion. Herodotus portrays Mardonius as the main instigator stating that he “wanted to stir things up and he wanted to become governor of Greece” (Herodotus 7.5). Diodorus too places heavy emphasis on Mardonius persuasion as a reason for Xerxes to take up the Greek expedition. He claims that Mardonius was “eager to be the leader of great armaments” (Diodorus 11.9.1) and thus persuaded Xerxes to invade Greece in order to achieve this. Diodorus was most likely following Herodotus’ account of the events as his version was written much later. However, it is interesting to note which motives he deems important enough to copy down. In Herodotus’ narrative Mardonius uses all kinds of manipulative speech in order to persuade the king to pursue Greek subjugation. This includes claims about Greek food, climate, and warfare which are exaggerated.  While the claims of climate may have been made out of ignorance (as is suggested by Stoneman) knowledge of Greek land and food must have been known about beforehand. Greece had trade routes in the Black Sea and with Egypt for food supply, all of which were under Persian rule at the time. Persia then would have known about Greece’s dependency on grain ships for food. Xerxes himself seems to be aware of this in Herodotus’ narrative when he is on his way to Greece and spots grain-ships sailing to Aegina and the Peloponnese. When asked about attacking the ships Xerxes is noted as saying:
Are we not bound ourselves to the same destination……I do not see that those ships are doing us any harm by carrying our grain for us (7.147).
While the quotation plays in with Herodotus’ repeated theme of hubris it also proves that the Persians must have had an idea of Greek dependency on others for grain. Evidence of trade between Athens and Persian-ruled areas of the east are also apparent. This comes in the form of archaeological evidence showing attic pottery that was found in eastern provinces and Achaemenid coinage in areas near Athens. This trade between Persian provinces and mainland Greece would have resulted in an exchange of information and culture. Lack of knowledge about Greece’s geography thus seems highly unlikely given the extent of contact with Persia at the time. Thus, Xerxes would have already had an idea of Greece’s geography and cuisine before Mardonius’ speech. This makes the speech itself appear less persuasive than Herodotus would have his readers believe. It should be noted, however, that Mardonius would have benefitted from the subjugation of Greece in terms of power. Thus his speech in Herodotus’ narrative should not be fully dismissed. While the role of Mardonius is no doubt played up as a motive behind the Greco-Persian wars, the persuasiveness of others present at Xerxes’ court should not be forgotten. This included Thessalian aristocrats and exiled Greeks such as the Peisistratids (Herodotus 7.6). Herodotus notes the Peisistratids especially attempting to persuade Xerxes to overtake Greece. They did this by employing the help of an oracle collector, Onomacritus. According to Herodotus, Onomacritus would recite favourable omens to Xerxes in order to convince him to invade Greece (7.6). The Peisistrads would have no doubt believed that the subjugation of Greece meant their reinstatement of power. The presence of Greek exiles at the Persian court is a common reoccurrence in Greek history, for example Democedes the doctor being present at the court of Darius (3.132). The presence of such people is not doubted. However, the extent of influence these people held on Persian politics is difficult to gauge. Herodotus would have his readers believe that these exiles or defectors were definite players in Persian policies. There would obviously have had to be mutual benefits for both parties to work with each other. From a Persian point of view these exiles would be seen as useful informants and potential governors of conquered areas.  The exiles would have wanted power back and given information to gain it. While their information would have been useful in Persian decision making it is unclear just how much the Persians relied on it or if they were using it to justify/confirm decisions already being made. Nevertheless Greek exiles held a degree of persuasiveness at the court of Xerxes. While it was most likely not a deciding factor for the war the exiles should be taken into consideration when evaluating potential motives for the Greek invasion.
Pro-Persian Feelings in Greece
The presence of established tyrants and exiles at the Persian court proves that some Greeks were more accepting towards the Persian Empire. The view was not as anti-medizing as historic sources have portrayed. As seen above many tyrants along the coast of Asia Minor owed much of their power to the Persians and this created a sense of loyalty. However, pro-Persian feelings can be seen clearly in many parts of Greece, (especially those more North) with factions who did not owe much to the Persians. For example Herodotus makes note of certain Athenians, who during Darius’ attempted invasion of Greece, were thought to be willing to betray the city. The story goes that the Alcmaeonidae were guilty of raising a shield to signal to the Persians to sail around Suniam in order to reach Athens after their slaughter at Marathon (6.123). Herodotus himself expresses doubtfulness at the family that is accused of betraying Athens, as they had a history of freedom fighting for the city. Herodotus is adamant however that the signalling happened stating “A shield was held up; that is a fact and cannot be denied” (6.124). Regardless of who held up the shield it proves a point that certain parties within Athens were willing to medize.  While this event took place during Darius’ reign it can be argued that the divide between Greeks willing to medize and those who were not continued into the reign of Xerxes. Herodotus makes note of Hellenic states who gave the submission token of earth and water to the Persians. This included Thessaly, Thebes, and most of Boetia (7.132). The acceptance of Persian rule by these factions can be explained by pointing out the advantages of doing such. On one hand it would make sense to side with Persia in order to gain power. This is something that the tyrants had used to their advantage and benefitted from. On the other, it was a way to preserve the safety of the factions. Persian rule often meant tribute and some sort of military service.  This would have been a low cost compared to the potential high costs of fighting against the Persian Empire. Herodotus notes many times in his narrative the massiveness of the Persian expedition (eg. 6.117 &7.184). While his numbers are debatable there is no doubt that this force would have been much larger than that of the Greeks. Herodotus also notes that during his march Xerxes was “compelling all in his path to join his expedition” (7.108). This only adds to the number the Greeks would have faced. It is logical then, for factions to have been nervous about fighting such a force. It should also be noted that Greek factions had a long history of fighting against each other rather than fighting with each other. This would have influenced factions’ ideas of the ability to come together and fight a common enemy. In fact it is more surprising that factions did end up fighting together for a common cause.  The fear of the Persians indicates that submission was a necessity for some factions as they did not see any other alternative. For some factions Persia may not have been the enemy at all. Both Athens and Sparta had dismissed the Persian embassies (in creative ways) but each would have had enemies within the Greek world. For example Athens and Aegina are noted as being at odds as a result of a theft of statues (5.84). Persian rule over Greece would have been beneficial to those who found themselves on the wrong side of either Athens or Sparta as it would even the playing field and perhaps offer those subjugated to the mainland powers (such as Argos) a way out. This indicates that it may not have been an acceptance of Persian rule so much as the dividedness of Greece that would have played a part in Persia’s decision to invade Greece. If Xerxes felt that he would not receive much opposition from many of the Greek states then an invasion would have been logical.
The Persistence of Persia’s Expansionist Policy
The city states of Greece may have felt that submission to the Persians was inevitable as Persia had a history of expansionist activities. This included actions taken during the Scythian expedition with the taking of Thrace and Macedonia. Activities closer in time to the Ionian revolt included the failed Naxos expedition undertaken by Megabyzus and, the main proprietor of the Ionian revolt, Aristagoras. Naxos was especially a blatant attempt at acquiring land following the motives mentioned in Herodotus. It is no surprise then that mainland Greece would have been next on the list. These expansionist actions were taken under Darius;
however there is evidence suggesting that Xerxes had adopted this ideology. Evidence can be seen with Xerxes’ speeches within Herodotus’ narrative. When Xerxes is giving his reasoning for invading Greece (and stating that he will burn Athens) he is also noted as stating that one of the advantages of the expedition will be the extending of Persian boundaries into “God’s own sky”. He also states that he intended to pass through Europe and “make it all one country” (7.8.C). Xerxes is later mentioned as proving this point during his expedition to Greece as he is noted as “compelling all in his path to join his expedition” (7.108). Herodotus’ depiction of Xerxes’ speeches are most likely made up. There would have been no way for Herodotus to know exactly what Xerxes had said as he would have not been present. However, as Herodotus was acquiring his information from other people it reflects what the Greeks would have thought Xerxes’ ambitions were. Thus, although what is being spoken should not be taken into account verbatim, there is a level of validity to what Herodotus has Xerxes say. Herodotus then reiterates Xerxes’ ambitions by stating “the whole country as far as Thessaly had been enslaved and was a tribute paying subject of the king” (7.108). This indicates that Xerxes’ march to Greece was not only for the purpose of subjugating only Hellenistic states or revenge. Greece would have been an understandable by-product of Xerxes main objective, Western Europe. The convincing of other factions to join him, most likely by means of subjugation, indicates that Xerxes was in fact on a mission to expand Persian territory.
Xerxes ultimately decides to pick up Darius’ unfinished campaign against mainland Greece. The animosity between Persia and Athens can be traced back before the Ionian revolt and may have been a factor in Xerxes’ decision to invade Greece. The idea of revenge as a main motive for the excursion is a repeated theme throughout Herodotus. While this may have been the case it does not appear to be a logical motive as the Persians had recently gotten revenge on Miletus for the Ionian revolt and Xerxes’ stated reasons for hostility towards the Athenians are strange. There is archaeological evidence suggesting that Athens was indeed sacked by the Persians. While this directs towards a revenge motive the indicators of the Persians burning sacred spaces in Athens may have served as a warning to other Greek factions fighting against the Persians. Xerxes also received pressures from those in his court to subjugate Greece. The stressed reasons to do so, given by his trustee Mardonius, are dubious as Xerxes would have had knowledge about the details of Greece being handed to him. Greek exiles were also present at the court of Xerxes placing their own pressures on him to invade Greece. Greek factions who were not on good terms with either Athens or Sparta would have seen it Persian rule as a potential stepping stone for their standing in Greece. They may have also been more accepting to Persian rule as they felt it was inevitable. Reading between the lines of Herodotus gives indication that Persia was continuing the expansionist policy that had been so obvious under Darius. This is seen with Xerxes’ subjugation of other nations on his way to mainland Greece and serves as a logical explanation for the excursion.
 Baragwanath 2008, 207.
 Cawkwell 2005, 87
 Green, 1996. 21
 Knowlton, 2016. 51
 Although Herodotus’ account is hard to follow seriously at this point it may indicate that Greece was not on the forefront of Xerxes’ mind and it may have taken him a while to get an expedition going.
 Ferguson 2016, 2.
 Ferguson 2016, 4.
 Stoneman 2016, 113.
 Stoneman 2016, 114.
 Green 2002, 78.
 Miller 1997, 67 & 73.
 Burns 1962, 130.
 Knowlton 2016, 49.
 Miller 1997, 1.
 Green 1996, 15.
 Green 1996, 51.
 It is interesting to note that Pro-Persian actions did not provoke any special punishments. Those accused of Medism were punished with the same legislative treatment as those accused of treason. See Graf 1984, 15 – 16
 Briant 2002, 405.
 Green 1996, 59.
 Baragwanath 2008, 205.
 Rhodes 2007, 34.
 Cawkwell 2005, 87.