After Marathon, the Athenians went back to their everyday routine and tried to solve their differences with Aegina (Her VI.88; Plut Vit Them 4,1), but to no avail. They ultimately failed embarrassingly and miserably (Her VI.93) and this enticed them to use the new revenue of silver in the southern tip of Attica, in Laurium, to build a fleet for this sole purpose (Her VII.144,1). The Spartans discovered that Cleomenes had manipulated the Oracle of Delphi to get rid of Demaratus, his co-king and Nemesis and were furious, deposing him (Her VI.74,1–75,1) and almost delivering Leotychidas, who had chastised and replaced him as an animal to the Aeginiteans (Her VI.85,1). The latter, instead of exacting vengeance for their hostage plight, they befriended to enlist his help in order to recover their hostages kept by the Athenians (Her VI.85,3). The Athenians refused to comply (Her VI.86–87), and Sparta and Aegina drew closer as a result; it is of interest, though, that the island state was since then firmly on the patriotic side, meaning that Cleomenes’ high-handedness uprooted the Medizers from the executive and influence bodies, at least in a functional sense. The very similar manipulation of the Alcmaeonids, to make the Spartans unseat the Peisistratids, which was the reason for the intervention of Cleomenes (Her V.90,1), a failed one due to undermining by Demaratus, was not taken into consideration by the Spartans at any point, indicating rather a fierce infight between the Kings and the Ephorate (Dickins 1912) hidden under issues of reverence.
Somehow, since 487 BC the Athenian constitution changed towards more militant formats (Burn 1962), as the radical naval party started, under Themistocles, gaining power. The naval party became prominent and Piraeus (re)started being built. The new, fortified port was supposed to be secure from enemy incursions, like the embarrassing Aeginitean raid in Phaleron circa 505 BC (Burn 1962), which predated the silver bonanza. It was showing that Athens turned to the sea to feed her population and it was her turn to the West, the only corn-producing area free from the Persian yoke, a move vividly enforced by Themistocles, which was slowly bringing her into conflict with the former ally Corinth. The increasing commerce increased the Hoplite class and the millionaires, who were to command, condition and care for the new-built triremes (Arist Ath Pol 22,7; Polyaen I.30,6). This approach is similar to the later concept of Trierarchs, in the age of Thucydides and may well have been the first step in that direction.
The naucraries were responsible for raising one vessel each for the Athenian navy and this vessel must have been supplied by one of the ship-owners belonging to the naucraria, or by money paid by the naucraria to such an owner from public funds (Arist Ath Pol 8; Haas 1985), possibly raised from the higher property class of Solon (Ridley 1979). Thus there was always a link between filthy-rich private individuals and naval vessels. Once, though, a trireme is required, which is ill-suited for anything but war, and especially for trade as it requires a massive crew and has very limited cargo capacity and sailing autonomy, the vessel had to come from the state, which became possible thanks to the silver mined from Laurium. But the outfit of the vessel and the maintenance of the crew must have been delegated to the rich Athenians, of the top property class. Thus, Herodotus mentions Cleinias, the father of Alcibiades as commanding his own trireme and the same for the Crotoniate Phayllus (Her VIII.17 & 47 respectively), but he might have been so specific just to please Periclean and Alcmaeonid ears. Still, there is some evidence that all the trierarchs were expected to cater for their crews; Architeles, the trierarch of the sacred state vessel was trying to effect a general withdrawal from Artemisium for lack of funds to pay his crew (Plut Vit Them 7,5).
Darius decided to take more drastic measures, perhaps to lead in person for one last time a royal army and thus initiated unprecedented preparations (Her VII.1). Innovations like fully amphibious campaigns, probably proposed by Datis (Burn 1962), were swept aside; however, some of the technological spin-offs, such as the horse transports, were retained. But death came for him in the mid-480s. He had picked Xerxes, one of his sons, born by Atossa, the daughter of Cyrus the Great, for his successor (Her VII.3,4) early on and had him in training as viceroy in Babylon (Green 1970). He appears as heir-apparent in sculptures and paintings. Herodotus mentions that Demaratus, the exiled king of Sparta proposed to Darius the institutional means needed to select Xerxes as his heir, who was not his firstborn. Darius’ ulterior motive was that this selection made the fusion of his bloodline with that of Cyrus secure (Llewellyn-Jones 2017).
Additionally, Darius must have taken into consideration other, more sinister aspects as he was himself a master conspirator. His friend Gobryas, with laurels against the insurgency in Elam in 520 BC (DB 71) was Chief of Artsibara, which is most probably an office equivalent to Royal Chamberlain, and thus he had been the number two in the realm after Darius (Fields 2007; Waters 2004; Sekunda 2002). Should his nephew, the prince Artobazanes (Her VII.2,2) Darius’ firstborn from Gobryas’ sister had become heir-apparent by right of the firstborn, instead of Xerxes, Darius might have found himself in peril and the line of Gobryas would evolve from ‘One of the Seven’ to the most prominent amongst the Six (Hyland 2018), almost of equal standing to Darius’ own. Any member of this bloodline might develop an appetite for further aggrandisement and consequent actions, like coups, murders etc. If the line of Cyrus, meaning Xerxes or any of Xerxes’ full brothers, was pushed to succession, Darius would be safer as this line was bereft of male members who might aspire to the throne. Darius had already favoured Xerxes, but the tradition pertaining to the firstborns had him entangled; Cambyses had been Cyrus’ firstborn (Her VII.2,3) and thus appointed viceroy at Babylon, although Smerdis was by far the better man. In this problem, Demaratus introduced to the Achaemenids the concept of ‘Born in Purple’ (Her VII.3,2–3), which gave Darius the solution he needed and Xerxes the status of heir-apparent and the seat at Babylon which implies a comfortable time before the death of Darius, probably circa 496 BC (Gertoux 2018). The above resulted in the new monarch being deeply indebted to the Spartan exile.
Still another issue is the temporal parameter. Herodotus’ account creates the notion that the issue of succession was settled shortly before the king’s death (Her VII.2), but Demaratus had been at Susa most certainly after Cleomenes’ failed campaign in Attica (Her V.73–5) but definitely before the Ionian Revolt, meaning somewhere between 510 and 500 BC. Demaratus’ presence in the royal court was a good reason for Cleomenes’ initial deliberation on and final abortion of the invasion of Asia suggested by Aristagoras (Her V.50). This suggests a date near 505 BC for Demaratus’ arrival at Susa and the issue of selecting the successor of Darius might have arisen at that time, long before Marathon, after Xerxes had served his tour of duty as an Arstibara. This timing would allow a proper breeding and some appropriate instruction as viceroy in Babylon (Holland 2005).
While Darius was making unprecedented preparations (Her VII.1,2) the Egyptians had had enough (Her VII.1,3). Their clergy had been on the best of terms with the impostor, as he had nullified the social policies of Cambyses, who was obviously copying his benevolent father (Holland 2005; Burn 1962). The original Satrap, Aryandes, sanctioned by Cambyses (Her IV.166,1), seemed to have been on perfect terms with the natives, suffering just one minor revolt, and that during the ascendance of Darius to the throne (Klotz 2015; Mumford 2019). Darius had him marked and found a stupid pretext to exterminate him (Her IV.166,2); but, then, he had no obligation to support his allegations and back his pretext, as he was the agent of Ahura-mazda (DB 52 & 56) and his word was by definition The Truth.
The new satrap must have been less co-operative and sterner; moreover, continuous demands for resources, in labour for the pharaonic undertakings, such as the canal between the Nile and the Red Sea and the palace at Susa, but mostly in wheat and gold for the continuous campaigns, were bankrupting the clergy and the populace (Mumford 2019). It is very doubtful whether Darius ever implicated Egyptian units in his campaigns. There are two exceptions: the Scythian campaign, when Herodotus declares that Darius led representative contingents from all his subject nations (Her IV.87,1); and the campaign to quell the Ionian revolt (Her VI.6). Under such circumstances, the Egyptians revolted and a new Pharaoh, Psamtik IV was inaugurated (Klotz 2015; Mumford 2019; Wijnsma 2019).
Darius died before being able to deal with the situation (Her VII.4), and Egypt reemerged partially, with a new native Pharaoh and a problem with the Persian administrative staff located there (Wijnsma 2019). Xerxes swiftly dealt with the situation, probably by dispatching the army prepared by Darius and not by leading it (Klotz 2015). When the army conquered, his brother Achaemenes was appointed satrap and savage retribution was exacted (Her VII.7); its religious nature suggest the hand of the native clergy in the uprising, and/or the religious fanaticism and intolerance of Xerxes as described in the ‘Daiva inscription’-XPh (Klotz 2015; Herzfeld 1932), and despite concerted efforts to interpret the latter in benign terms (Kuhrt 1997; Abdi 2007).
Most scholars agree that there were two rebellions in Babylon after Xerxes was enthroned and before his campaign in Greece (Ossendrijver 2018; Waerzeggers 2018). It is true that Xerxes ultimately struck the Babylonian titles from his royal etiquette (Waerzeggers 2018; Llewellyn-Jones 2017). This says little; it could be because he left them to the viceroy of Babylon, as he had been. But Herodotus mentions a satrap, not a viceroy, later in Babylon (Her VII.62,2), which means Xerxes abolished the Trinity introduced by Cyrus and confirmed by Darius; he had not appointed one of his sons as viceroy, the heir-apparent, but established a nobleman as satrap.
Moreover, in Xerxes’ campaign Herodotus, and Diodorus, mention no Babylonian contributions. There were contributions from the area (Her VII.63), but not from Babylon, and Aeschylus’ contrary testimony (Persai 52–4) in this case may well be due to poetic licence. This proves that before Xerxes invaded Greece there was at least one Babylonian uprising, and it was dealt with swiftly and savagely (Waerzeggers 2018; Llewellyn-Jones 2017). There is no need to assume a second one, and, even more important, we do not need to assume this first uprising taking place after his coronation in 486 BC, although some arguments do indeed corroborate it (Llewellyn-Jones 2017). It could have been during his years as a viceroy (Gertoux 2018), and one may dare to blame his religious zeal in a city most liberal, at least in terms of scruples. The second rebellion must have been during his sojourn in Greece (Mumford 2019; Waerzeggers 2018; Llewellyn-Jones 2017), most probably after the battle of Salamis, a perfect reason to expedite his return (Her VIII.103) and to stay for quite some time in Sardis instead of returning to Susa (Her VIII.117,2). As in Egypt, he dispatched someone to do the job and in this case, we have a name: Megabyzus (Burn 1962; Green 1970), one of his six marshals (Her VII.82). He was the son of Zopyrus, who had reconquered Babylon for Darius and he himself did it for Xerxes, probably to quell the second rebellion which had claimed the life of his father Zopyrus, established in Babylon as Satrap (Gertoux 2016) after Xerxes had advanced to kingship.
In any case, the safe conclusion is that once the army of the Egyptian expedition was back and disbanded and Achaemenes firmly established at the satrapal seat (an indication that he had commanded the task force sent to crush the rebellion), Xerxes dwelt upon the Greek expedition. With two major revolts in ten years, if not three, he might have been skeptical. The wisdom of straining the resources for a massive European campaign, not only against Greece, could cause further dissatisfaction. On the other hand, success could well bring in a hefty profit, not only from spoils, slaves and from hammering the imperial identity into dissatisfied subjects, but also from the increase of his own splendour, radiance and prestige as a warrior king. This was his prerogative: a warrior chosen by warriors (Fields 2007), as inscribed on Darius’ grave (Dnb 9). Once his mind had been made up, Xerxes hated half-measures and novelties to the tune of the campaign of Datis. He liked grandiose things. After all, he was to take the field himself this time. But it must be noted that the spirit of Datis was living and his house suffered no dishonour due to the defeat: his two sons were the two out of three cavalry generals (Her VII.88,1) and, more importantly, the fleet would not move independently but would be augmented with a most powerful marine contingent (Her VII.184,2) which included masses of cavalry, with mounts loaded on horse transports (Her VII.97).