The fiercest challenge yet both to Pericles' leadership and to the unity of the Delian League arose in 441 from a dispute with the island city-state of Samos, one of the few alliance members still fielding a strong navy of its own. The Samians and their neighbors on the mainland in the city-state of Miletus, also a league member, had reached an impasse in a heated conflict to take over some nearby territory. The Athenians instructed their arguing allies to go to arbitration, but Samos refused. Pericles probably proposed the decision made by Athens as leader of the Delian League to respond very forcibly by installing a new, and democratic, government on Samos; in supporting this policy unfavorable to the elite of Samos, Pericles was perhaps recalling the treachery of those Samian commanders fifty years earlier who had made a deal with the Persian king Darius to save their city-state from what they feared would be devastation and therefore deserted the Ionian alliance in the heat of the Battle of Lade. A fine of 80 talents was imposed, and 100 citizens were taken away as diplomatic hostages to an Athenian stronghold on the island of Lemnos. In keeping with his conspicuous incorruptibility, Pericles refused a king's ransom in bribes offered him by a group of rich antidemocratic Samians and the Persian governor to ease the conditions.

The next year, the dispute blew up into a crisis that restored the Persians to the status of an active threat to the member states of the Delian League when the Samian rebels allied with the Persian governor in western Anatolia. Now flush with money supplied by the Persian king's governor, they hired mercenaries and violently overthrew the newly installed democracy allied with Athens. The anti-Athenian Samians also freed the hostages and captured some Athenian citizens. These fellow Greeks they turned over to their Persian backer. The city-state of Byzantium then joined the rebellious Samians in rebelling against the league.

To meet this serious crisis to the league's unity and to the safety of his fellow citizens who were being held as hostages, Pericles was tasked with commanding a force of warships from Athens supported by the fleets of Chios and Lesbos.

When in the summer of 479 the teenaged Pericles finally learned of the allies' astonishing victory over the Persians at Plataea, he could rejoice for his city-state and Greece though worrying about his father. Xanthippus was still away from home, commanding the Athenian warships in the allied fleet that sailed east across the Aegean Sea to respond to the plea of the Greeks in Ionia to free them from the Persian Empire. Now that the allied coalition had repulsed the great invasion of central Greece, the Ionians began to hope the momentum of that victory could be leveraged to force their release from the Great King's control. This continuation of hostilities with the Persians was to have a monumental significance for the history of Athens and the career of Pericles, as alluded to before, because it led to the beginning of what scholars today call the Athenian Empire.

Since the Persian commanders on the Ionian coast in 479 decided their fleet was inadequate to confront the Greek alliance at sea, they disembarked their men onto the Mycale peninsula, opposite the island of Samos. The Greeks followed them onto the land, crushing their opponents in a fierce battle in which the Athenians won the prize as the best fighters by punching through the center of the enemy line. Xanthippus' reputation for military leadership soared as a result. Among the spoils seized by the victors were chests spilling over with valuables; the Persians always took a store of treasure along on their military expeditions. The Greeks were learning that success in battle against them could be lucrative.

The Greek allies next held a conference on the island of Samos just off the coast of Ionia to debate the fate of the Greeks who were pleading for liberation. The Peloponnesians, headed by the Spartans, made the startling proposal that the Ionians should be forced to evacuate their homes and abandon their land to the Persians. It seemed impossible to defend this region forever, went the Spartan argument, and the Ionians could be resettled in the west in territories that would be seized from Greeks who had Medized in the Persian Wars. Those traitors would be punished by being expelled to fend for themselves as homeless refugees.

Pericles reached his teenage years in the later 480s. He was growing up in an Athens that was becoming mainland Greece's most populous city-state, the term that modern scholars have adopted to describe ancient Greek political communities consisting of a large urban center controlling a territory also populated with smaller outlying villages and farmsteads. Citizens could live anywhere in the city or the countryside. The Greek word for city-state was polis, the source of the modern word “politics.” During the fifth century, the number of adult male citizens entitled to exercise political rights and required to serve in the citizen militia probably crested somewhere between 40,000 and 60,000. Overall, the polis of Athens grew to a population that probably totaled 250,000 or more, counting everyone: male and female citizens and their children, resident foreigners, and slaves. This was an extremely large population for an ancient Greek polis. Of the more than 1,000 ancient city-states whose existence is documented, most had far, far smaller numbers of people residing within their borders.

The territory of Athens, known as Attica, occupied a triangular peninsula of plains, hills, and small mountains in southeastern mainland Greece. Athenians, like the inhabitants of other Greek city-states, devoted the majority of their land to agriculture, but they were especially fortunate to have a coastline dotted with good ports for sea commerce. By the time Pericles was an adult, the population of Attica had grown so large that it outstripped the land's capacity to produce enough food to feed everyone. Merchants therefore began to import large amounts of essential supplies, especially raw grain, from fertile areas to the northeast in the Black Sea region and to the southeast in Egypt. These bulk imports of grain were transported aboard ships plying the Mediterranean Sea, which made for a risky business enterprise because storms could easily wreck the transport vessels.

Porridge and bread made from barley and wheat, supplemented by vegetables, olive oil, and cheese, represented the main source of nutrition for ancient Greeks. Most people could not afford meat as a regular item in their diets, and they therefore highly valued the distribution of cooked portions from large-scale animal sacrifices financed by the state.

One night in Athens in the mid-490s B.C. (the exact year is unknown), a rich and heavily pregnant woman named Agariste had a dream: she saw herself giving birth to a lion. A few days later her second son was born, and his parents named him Pericles. Ancient Greeks traditionally believed that dreams were sent from the gods, as they learned from the epic poems The Iliad and The Odyssey by Homer; his famous stories explored the sufferings caused by the Trojan War and expressed foundational beliefs of Greek culture. From listening to myths about ancient heroes and from hunting lions, which still roamed Europe in antiquity, Greeks learned that these animals were both powerful defenders of their own group and fierce destroyers of their prey. Agariste understood her dream to be a divine message indicating that her child was to become a very special person, for good or for bad – or for both.

Agariste's premonition about her child's future prominence proved accurate. Pericles at the height of his career became the most famous leader of the most famous and radical democracy of the most famous place of the most famous era of ancient Greece (Figure 1). During Pericles' lifetime in the fifth century B.C. (he died in 429), Athens became Greece's most influential incubator of far-reaching cultural developments, from scientific and philosophical ideas to innovative forms of art, architecture, and theater. This aspect of Athenian history has gained an appreciative reception in later times. Far less positive, however, has been the assessment of the actions of the Athenians toward other Greeks in this same period as they transformed themselves from their previous second-rate international status into their region's wealthiest and strongest military power. By the 430s, they controlled numerous other Greek allies in what Pericles memorably called a tyranny, according to the contemporary historian and military commander Thucydides (The Peloponnesian War 2.63); other contemporaries echoed that judgment, adding that Pericles led Athens as a de facto tyrant. Many modern scholars agree, labeling the Athenian-dominated alliance an empire and Pericles an imperialist, implying all the deeply negative connotations of those terms in their modern context of colonialism and oppression.

Like other sons from elite families in fifth-century Athens, Pericles while a child was taught to read, write, do basic arithmetic, and perform, or at least study, music. Boys with wealthy backgrounds often received their early education from educated slaves owned by their families or from private tutors (Figure 10). Publicly funded schools were rare at this point in Greek history. In the next stage of his education, Pericles would have focused on developing rhetorical skill as a public speaker, as preparation for making persuasive speeches to juries in court cases, in the Council of 500 that set the agenda for the assembly and conducted other public business, and at the mass meetings of the assembly. These venues were manned by groups of male citizens numbering from the hundreds to the thousands, and they were ready to shout out criticisms of ineffective orators while they were still trying to speak to the audience. Once Pericles and his contemporaries from the upper class reached their mid- to late teens, they began accompanying their fathers and uncles to be spectators as these older relatives attended meetings and gave speeches. This informal apprenticeship allowed the youngsters to observe successful – and failed – speakers, absorbing lessons about how to conduct themselves effectively in the highly combative environment of Athenian democratic politics.

Only those speakers could succeed whose arguments demonstrated a strong knowledge of history, finance, and politics; whose use of language was intelligent and artful; whose voice was strong enough to make them clearly audible when addressing large crowds both indoors and outdoors; and whose personal toughness enabled them to withstand intense public scrutiny that often involved mockery and heckling. As Pericles in the 460s approached thirty years of age, he knew he needed special training to overcome the daunting hurdles that awaited him on his quest to become a respected and influential leader in war and peace.

A new way for young men to prepare for public careers developed in Pericles' time, a change from tradition that he embraced with enthusiasm. By the mid-sixth century, innovative Greek thinkers had been impressing – and shocking – other Greeks with their controversial ideas about the nature of the world.

When Agariste gave birth to her second son, women surrounded her and the new baby, as was usual during childbirth in ancient Greece. Mothers delivered babies at home, and no men were in the room. As in everyday life, female family members and household slaves controlled parts of the house that were regarded as off-limits to men. Ancient Greek fathers had relatively little direct interaction with newborns, but as the head of the household the husband had the legal right to reject the infant as illegitimate and refuse to raise it. If a father took this extreme (and rare) step, his decision obliterated the child's identity as a free citizen and condemned the helpless babe to being abandoned in the streets for anyone to find – and to sell or keep as a slave.

Family history and personal networks had an enormous influence on Athenians' lives because newborn children in ancient Athens entered a world in which deeply consequential decisions about their status began the moment they emerged from the womb and continued until they were adults: Were they genuinely their father's offspring? Were they going to be recognized as legitimate and so be raised as free members of the household? Would they later be accepted into the hereditary group (phratry) whose membership affected their social standing? Finally, in their late teenaged years would they be validated as full citizens by the members of the local subcommunity (deme) to which their father's family had always belonged? (There were some 130 to 140 separate demes constituting the Athenian democratic state as a whole.) The family, relatives, and neighbors of the children made these crucial judgments; the central government was not regularly involved in the life-altering decisions that decided individuals' status as free or slave, citizen or noncitizen.

About a week after his son's birth, Pericles' father, naked, as tradition required, picked up the new infant to carry him around the hearth. He then conducted a sacrifice, signaling the legitimacy of the child and its acceptance into the family. The joyous celebration moved on to a traditional meal of octopus and squid enjoyed with relatives. A few days later, the baby boy's parents followed tradition by formally proclaiming his name.

In the 440s Pericles won his way to the top in the contest for leadership in democratic Athens. It was a time of almost nonstop conflict in foreign affairs and domestic politics. The Spartans followed up their rejection of Pericles' proposal for Greek unity by sending a military expedition to Delphi to secure their own primacy at Apollo's shrine. The Athenians countered this move after the Spartans returned home by sending Pericles to command an expedition to the god's sanctuary to reverse the arrangements that their enemies had made. He had the name of the Athenians inscribed on the statue of a bronze wolf in the sacred precinct to show that petitioners from Athens received the privilege of going to the head of the line of people waiting to consult the oracle, displacing the Spartans from that treasured advantage. The five-year peace that Athens and Sparta had agreed to in 451 was obviously fraying.

As usual, the chronology of events is confused in the ancient sources, but it is clear that Pericles was now playing a major role as a military commander in campaigns outside Athenian territory. Still, Athens had no second Cimon in the sense of a general whom the people regarded as far and away their best, and Tolmides' military reputation seems to have been as prominent as Pericles' in the early years of the decade. Pericles did, however, win great acclaim for the expedition he led in about 447 to the Thracian Chersonese. Ancestors of Cimon had long before settled Athenians on this peninsula, whose cities controlled the strait through which crucial imports of grain and timber were transported south from the shores of the Black Sea. The Thracians had never been happy about this encroachment, and they constantly raided the Greeks' settlements.

Pericles reestablished the Athenian presence in this strategically important region by recruiting and transporting a large group of new settlers to occupy the land and building a defense wall four miles long to reach from shore to shore across the neck of the peninsula. It seems possible that Pericles was aided in this innovative plan by recalling information about the region that he had long before learned from his father, who had been the Athenian commander in a victorious campaign in the Chersonese at the end of the Persian Wars.

The years from 511 to 507 had been tumultuous for Athenians. Cleisthenes had redirected their government in the direction of a strongly direct democracy, they had repulsed by force the attempt to seize control of their state by Cleomenes of Sparta and his Athenian collaborator Isagoras, and they had made the fateful decision to ask the Persian king for a protective alliance. As the next decades would reveal, the events of these few years deeply affected the social and political conditions of the Athens into which Pericles was to be born in the mid-490s. They also taught harsh lessons pertinent to his own career that Pericles would learn from his parents' stories about the history of Athens when they themselves were young. Those maxims were easy to summarize but disturbing to contemplate. For one, trusting the Spartans was disastrous; they might claim to support liberation, but they could do an abrupt about-face and promote tyranny when it suited them. For another, the Greeks bordering on Athenian territory (the region called Attica) were also untrustworthy; the Athenians lived in a very treacherous neighborhood with much to fear. Home was also politically hazardous; some Athenians were willing to subvert democracy and resort to tyranny or oligarchy to promote their own advantage. Finally, Pericles could always expect his opponents to try to make trouble for him by exploiting his Alcmeonid lineage and the curse attached to his mother's family. The history of the years and decades to follow would confirm and expand these warnings for Pericles as he grew up.

Pericles' mother, Agariste, married his father, Xanthippus, around 500 or a few years later. Her first child was a son, Ariphron, named after her husband's father, as was customary. She also had a daughter, but neither the baby girl's birth order nor her name is preserved in the ancient sources. Agariste was probably in her late teens at the time of the marriage, Xanthippus in his mid- to late twenties. This difference in age was customary at Athens for brides and grooms in the upper class. When Xanthippus married into the Alcmeonid family, he was stepping up the social ladder. His name, meaning something like “Blond Horse,” was a kind of “horsey” name with an upper-class sound that richer Greeks liked to give their children.

In about 464, not long after the Thasian envoys arrived to persuade the Spartans to attack Athens, a giant earthquake devastated Sparta. The seismic shock knocked down almost every building in town, crushing countless people. The helots, the massive slave population that the Spartans kept under oppressive control across the southern Peloponnese, seized the moment to rebel, and very violently. They were joined by some of the Greeks from Laconia (Sparta's territory) called perioikoi (“those who live around [us]”), who were dominated, but not enslaved, by the Spartans. The rebels slaughtered their oppressors among the ruins of Sparta and then established a fortified settlement on Mt. Ithome in Messenia to the west. Forced to fight to preserve their very existence, the Spartans could not fulfill their promise to the Thasians to invade Athenian territory.

As a result, the islanders found themselves on their own in their besieged city. By probably 462 (the chronology of all the events being narrated here for the late 460s is debatable), the citizens of Thasos had to surrender to the Athenian-led attackers. The treatment of the defeated islanders was harsh. They had to turn over their navy, their mines, and their territory on the mainland to the Delian League and demolish their fortification wall (Figure 12). Despite being deprived of the revenue from their former mineral resources and commercial outposts, they also had to pay a large fine and then resume their payments to the alliance. In evaluating the fate of Thasos, it is necessary to recognize that the Athenians had not acted alone but in company with other league members and that it was both appropriate and necessary to compel the rebel Thasians because they had originally sworn a sacred oath never to leave the alliance. For that reason, the citizens of Athens as the leaders of the Delian League surely saw their actions as justified in enforcing the strict letter of the law, as it were.

At the same time, however, it is also likely that the rebellion of Thasos involved a dispute with Athens centering on a competition for riches and resources. Taking over Thasians' mines of precious metal and gaining control of the exploitation of and international trade in the extensive mineral resources of Thrace seem to have laid the financial base for Athens' growing prosperity during the middle decades of the fifth century.