Sparta, probably distracted (or left weakened) by…

The Greek task force had achieved initial successes, but they have been unable to capture the Persian garrison in Memphis despite a three-year long siege.

A strong internal federation, along with Athenian aid, enables the Phocians to regain control of the oracle at Delphi in 457 at the beginning of the “Second Sacred War” against Phocis.

…on the Spartans' return from Doris in 457 BCE, however, the land armies of Sparta and Athens meet at Tanagra in Boeotia.

Cimon presents himself to the Athenian generals and begs leave to fight in the ranks but is refused.

He adjures his personal followers, suspected like him of favoring the Spartans, to fight bravely, and they all perish in the large-scale but indecisive battle; …

…perhaps this event causes a revulsion of bitter feeling against Cimon.

In any case, Pericles himself, who has succeeded the assassinated Ephialtes as head of the democratic party, proposes and obtains an abbreviation of Cimon's exile.

On his return, he works for peace with Sparta, and is said to have been allowed to resume the war with Persia, much preferred to fighting other Greeks.

Athens makes an alliance (almost certainly in 457 BCE) with Segesta, an inland half-Greek Sicilian city; ...

…elsewhere in Sicily, Naxos stands in opposition to Syracuse after 461 BCE.

Ducetius, a Hellenized leader of the Siculi, seizes his opportunity to weld the native communities of east Sicily into a powerful federation during the confusion that follows the collapse of tyranny in Syracuse and other Sicilian states in 460 BCE.

Enjoying the goodwill of the Syracusan democracy, he enlists its help in driving out the colonists of the former tyrant Hiero from Catana and restoring it to its original Chalcidian inhabitants.

Ducetius now extends his influence over other communities and establishes a new center at Palice.

The Egyptian-Athenian victory is short-lived: the Persians, led by Megabyzus, the new satrap of Syria, together with Artabazus, satrap of Phrygia, who arrive in 456 BCE, now counterattack, confronting the Athenian fleet blockading Memphis, destroying two squadrons and confining the remainder of the Greek fleet, along with the Egyptian rebels, to an island in the Nile, where the Persians besiege them.

Charitimides is killed and Inarus is wounded in the thigh by the Persian force; he retreats to Byblus, his stronghold and the only Egyptian city that does not submit to Megabyzus.

The Athenians in 456 BCE defeat the Thebans at Oenophyta, which will give them control of Boeotia for a decade, an extremely important development.