Periclean strategy
First Peloponnesian War: Pericles made his first military excursions during the First Peloponnesian War, which was caused in part by Athens' alliance with Megara and Argos and the subsequent reaction of Sparta. In 454 BC he attacked Sicyon and Acarnania. He then unsuccessfully tried to conquer Oeniadea on the Corinthian gulf, before returning to Athens. In 451 BC, Cimon returned from exile and negotiated a five years' truce with Sparta after a proposal of Pericles, an event which indicates a shift in Pericles' political strategy. Pericles may have realized the importance of Cimon's contribution during the ongoing conflicts against the Peloponnesians and the Persians. Anthony J. Podlecki argues, however, that Pericles' alleged change of position was invented by ancient writers to support "a tendentious view of Pericles' shiftiness".
Plutarch states that Cimon struck a power-sharing deal with his opponents, according to which Pericles would carry through the interior affairs and Cimon would be the leader of the Athenian army, campaigning abroad. If it were actually made, this bargain would constitute a concession on Pericles' part that he was not a great strategist. Kagan's view is that Cimon adapted himself to the new conditions and promoted a political marriage between Periclean liberals and Cimonian conservatives.
In the mid-450s the Athenians launched an unsuccessful attempt to aid an Egyptian revolt against Persia, which led to a prolonged siege of a Persian fortress in the Nile Delta. The campaign culminated in disaster; the besieging force was defeated and destroyed. In 451–450 BC the Athenians sent troops to Cyprus. Cimon defeated the Persians in the Battle of Salamis-in-Cyprus, but died of disease in 449 BC. Pericles is said to have initiated both expeditions in Egypt and Cyprus, although some researchers, such as Karl Julius Beloch, argue that the dispatch of such a great fleet conforms with the spirit of Cimon's policy.
Complicating the account of this period is the issue of the Peace of Callias, which allegedly ended hostilities between the Greeks and the Persians. The very existence of the treaty is hotly disputed, and its particulars and negotiation are ambiguous. Ernst Badian believes that a peace between Athens and Persia was first ratified in 463 BC (making the Athenian interventions in Egypt and Cyprus violations of the peace), and renegotiated at the conclusion of the campaign in Cyprus, taking force again by 449–448 BC.
John Fine, in contrast, suggests that the first peace between Athens and Persia was concluded in 450–449 BC, due to Pericles' calculation that ongoing conflict with Persia was undermining Athens' ability to spread its influence in Greece and the Aegean. Kagan believes that Pericles used Callias, a brother-in-law of Cimon, as a symbol of unity and employed him several times to negotiate important agreements.
In the spring of 449 BC, Pericles proposed the Congress Decree, which led to a meeting ("Congress") of all Greek states to consider the question of rebuilding the temples destroyed by the Persians. The Congress failed because of Sparta's stance, but Pericles' intentions remain unclear. Some historians think that he wanted to prompt a confederation with the participation of all the Greek cities; others think he wanted to assert Athenian pre-eminence. According to the historian Terry Buckley the objective of the Congress Decree was a new mandate for the Delian League and for the collection of "phoros" (taxes).

Remember, too, that if your country has the greatest name in all the world, it is because she never bent before disaster; because she has expended more life and effort in war than any other city, and has won for herself a power greater than any hitherto known, the memory of which will descend to the latest posterity.
During the Second Sacred War Pericles led the Athenian army against Delphi and reinstated Phocis in its sovereign rights on the oracle. In 447 BC Pericles engaged in his most admired excursion, the expulsion of barbarians from the Thracian peninsula of Gallipoli, to establish Athenian colonists in the region. At this time, however, Athens was seriously challenged by a number of revolts among its subjects. In 447 BC the oligarchs of Thebes conspired against the democratic faction. The Athenians demanded their immediate surrender, but after the Battle of Coronea, Pericles was forced to concede the loss of Boeotia to recover the prisoners taken in that battle. With Boeotia in hostile hands, Phocis and Locris became untenable and quickly fell under the control of hostile oligarchs.
In 446 BC, a more dangerous uprising erupted. Euboea and Megara revolted. Pericles crossed over to Euboea with his troops, but was forced to return when the Spartan army invaded Attica. Through bribery and negotiations, Pericles defused the imminent threat, and the Spartans returned home. When Pericles was later audited for the handling of public money, an expenditure of 10 talents was not sufficiently justified, since the official documents just referred that the money was spent for a "very serious purpose". Nonetheless, the "serious purpose" (namely the bribery) was so obvious to the auditors that they approved the expenditure without official meddling and without even investigating the mystery.
After the Spartan threat had been removed, Pericles crossed back to Euboea to crush the revolt there. He then punished the landowners of Chalcis, who lost their properties. The residents of Histiaea, meanwhile, who had butchered the crew of an Athenian trireme, were uprooted and replaced by 2,000 Athenian settlers. The crisis was brought to an official end by the Thirty Years' Peace (winter of 446–445 BC), in which Athens relinquished most of the possessions and interests on the Greek mainland which it had acquired since 460 BC, and both Athens and Sparta agreed not to attempt to win over the other state's allies.

Final battle with the conservatives: In 444 BC, the conservative and the democratic factions confronted each other in a fierce struggle. The ambitious new leader of the conservatives, Thucydides (not to be confused with the historian of the same name), accused Pericles of profligacy, criticizing the way he spent the money for the ongoing building plan. Thucydides initially managed to incite the passions of the ecclesia regarding these charges in his favor. However, when Pericles took the floor, his resolute arguments put Thucydides and the conservatives firmly on the defensive. Finally, Pericles proposed to reimburse the city for all questionable expenses from his private property, with the proviso that he would make the inscriptions of dedication in his own name. His stance was greeted with applause, and Thucydides was soundly, if unexpectedly, defeated. In 442 BC, the Athenian public voted to ostracize Thucydides from the city for 10 years and Pericles was once again the unchallenged ruler of the Athenian political arena.

Athens' rule over its alliance: Pericles wanted to stabilize Athens' dominance over its alliance and to enforce its pre-eminence in Greece. The process by which the Delian League transformed into an Athenian empire is generally considered to have begun well before Pericles' time, as various allies in the league chose to pay tribute to Athens instead of manning ships for the league's fleet, but the transformation was speeded and brought to its conclusion by Pericles.
The final steps in the shift to empire may have been triggered by Athens' defeat in Egypt, which challenged the city's dominance in the Aegean and led to the revolt of several allies, such as Miletus and Erythrae. Either because of a genuine fear for its safety after the defeat in Egypt and the revolts of the allies, or as a pretext to gain control of the League's finances, Athens transferred the treasury of the alliance from Delos to Athens in 454–453 BC.
By 450–449 BC the revolts in Miletus and Erythrae were quelled and Athens restored its rule over its allies. Around 447 BC Clearchus proposed the Coinage Decree, which imposed Athenian silver coinage, weights and measures on all of the allies. According to one of the decree's most stringent provisions, surplus from a minting operation was to go into a special fund, and anyone proposing to use it otherwise was subject to the death penalty.
It was from the alliance's treasury that Pericles drew the funds necessary to enable his ambitious building plan, centered on the "Periclean Acropolis", which included the Propylaea, the Parthenon and the golden statue of Athena, sculpted by Pericles' friend, Phidias. In 449 BC Pericles proposed a decree allowing the use of 9,000 talents to finance the major rebuilding program of Athenian temples. Angelos Vlachos, a Greek Academician, points out the use of the alliance's treasury, initiated and executed by Pericles, as one of the largest embezzlements in human history; this misappropriation financed, however, some of the most marvellous artistic creations of the ancient world.

Samian War: The Samian War was one of the last significant military events before the Peloponnesian War.