Cimon's death makes diplomacy imperative in the eastern sphere.

Apparently, a peace with Athens, advantageous to Persia, is signed in 449 BCE, whereby the Persians agree to stay out of the Aegean and the Athenians agree to leave Asia Minor to the Achaemenids.

The diplomat Callias, a notable member of one of the wealthiest Athenian families, who is said to have distinguished himself in the Greek victory over the invading Persians at Marathon and to have won the chariot race at the Olympic games three times, negotiates this so-called Peace of Callias (mentioned by Diodorus but one of Thucydides' most famous omissions).

Pericles now embarks on a policy designed to secure Athens' cultural and political leadership in Greece.

If peace with Persia has not ended the alliance of the Delian league, it may have ended the annual tribute paid to its treasury, transferred in 454 from Delos to Athens.

Whether to regain this tribute, or simply to assert Athenian leadership, Pericles summons a conference of all Greek states to consider the questions of rebuilding the Greek temples destroyed by the Persians, the payment of sacrifices due to the gods for salvation, and the freedom of the seas.

Sparta will not cooperate, but Pericles continues on the narrower basis of the Athenian alliance.

Tribute is to continue, and Athens will draw heavily on the reserves of the alliance for a magnificent building program centered on the Acropolis.

Phocians, claiming the right to administer the shrine of Apollo, had taken control of Delphi by 450 BCE; the Amphictyonic League, with which Athens has made an alliance, protests that control of both the city and shrine rightfully belongs to them.

Sparta, entering for the first time into the concern of the league in 449 BCE, sends troops to expel the Phocians, who apparently depart without resistance, but Pericles dispatches Athenian troops to reinstate them.

Athens, a league member, then signs a treaty with Sparta, a unilateral action that angers the other members.

The Thebans rebel, unchallenged by Athens, and the Phocians, their alliance to Athens no longer in effect, retain control of Delphi.

An unstable peace in 448 BCE ends this so-called Second Sacred War.

Pericles, in establishing one of the new Athenian colonies, engages in his most admired campaign, the expulsion of barbarians from the Thracian Chersonese (Gallipoli), to which he sends one thousand additional settlers (cleruchs) in about 448 BCE.

Eyewitness accounts written by Herodotus, who is the principal source for much of the history of this and previous ages, indicate that he traveled in Egypt probably sometime after 454 BCE or possibly earlier in association with Athenians, after an Athenian fleet had assisted the uprising against Persian rule in 460-454 BCE.

He probably traveled to Tyre next and then down the Euphrates to Babylon.

For some reason, probably associated with local politics, he subsequently found himself unpopular in his native Halicarnassus and migrated sometime around 447 BCE, to Periclean Athens, a city for whose people and democratic institutions he declares his open admiration (V, 78) and where he come to know not just leading citizens such as the Alcmaeonids, a clan whose history features frequently in his writing, but also the local topography (VI, 137; VIII, 52-5).

According to Eusebius and Plutarch, Herodotus was granted a financial reward by the Athenian assembly in recognition of his work and there may be some truth in this.

It is possible that he applied for Athenian citizenship—a rare honor after 451 BCE, requiring two separate votes by a well-attended assembly—but was unsuccessful.

Herodotus is the first to use the term “delta” (from the Greek letter) in referring to the triangular alluvial deposits at the mouth of the Nile River.

Callicrates, together with fellow architect Ictinus, begins supervising the construction of the Parthenon on the Athens Acropolis in 447, a project entrusted to them by Pericles.

Phidias begins work on the gold and ivory statue of Athena that the Parthenon is to house.

The Acropolis project is to include, among other things, a temple to Victory and the Propylaea (started 437), the entrance gateway, far grander and more expensive than any previous Greek secular building.

Athens faces a crisis in 447-446, when oligarchic exiles, headquartered at Orchomenus, lead the cities of Boeotia, under Athenian control since 458, in a revolt, …

…beating a small Athenian army at Boeotian Coronea and …

…reconstituting the Boeotian league in alliance with Sparta.

A revolt follows in Euboea, crucial to Athenian control of the sea and food supplies.

Pericles crosses over to deal with it but only precipitates a third revolt, …

…that of Megara, which had been forced to accept Athenian defensive assistance after 461 BCE.