Here it is.
The main departure from OTL will be the absence of that plague that killed Pericles. He has to survive. The conservative Pericles strategy can't be transformed into the aggressive Demosthenes strategy as it was after his death.
Athens will rely more on defending it's own colonies, and protecting the fortified cities themselves. Technically Athens has better abilities to survive a war of attrition, because it has:
1. Overseas allies.
2. A good route of supply for Athens.
3. Pericles.
Now, Sparta had a large army to maintain, (the longest Spartan campaign into Athens was only 40 days) and also the helots to worry about.
Pericles stayed patient, and finally the Spartans, infuriated by the years of back and forth campaigning, attempted a direct assault of Athens, trying to storm it. It failed, the Spartans and their allies took some sections of the long walls, but not after losing many men. They are outnumbered and pushed back at a skirmish in Piraeus.
The Peloponessian Coalition starts to fracture. A helot revolt puts Spartan hegemony of the Peninsula in danger, and troops are withdrawn to put this down, giving Athens time to recover.
Sparta hadn't been dealt a devastating defeat yet, but it had certainly been humiliated. Athens managed to seize Megara as Plataia and Argos joined the allied coalition.
Next, Boiotia went over to Athens as Plataia and Delphi skirmished the forces of Thebes to a standstill. With the help of Athenian raids from Euboea, they keep Thebes under siege for the remainder of the war. Most of Attica, Boiotia, and Fokis are now under the control of Athens. Sparta during all this time hasn't been idle. They have attempted to assemble a navy, but are about as successful as the early Roman version, except that the Spartans don't have seafaring allies. They do manage to sack Naxos and Delos, but are crushed by the Athenian Navy at the battle of Melos.
So anyway, Sparta assembled it's largest army yet, (even encluding some helots which was quite revolutionary, but necessary due to the serious lack of manpower by now) and prepared to leave the Peloponesse. Their campaign plan was quite good, first to march from Korinthos to retake Megara, then send a diversionary thrust towards Athens. This is merely to distract them, because the real attack would then capture Plataia, (lifting the siege of Thebes) and then crush Delphi, effectively leaving Athens isolated and alone on Greece proper.
Sparta could then besiege the city and take it at their leisure, weakened as they believed it already was from the earlier assault. There was only one flaw in the Spartan plan, that they had forgotten as their massive army issued out of Sparta, Pylos and Mantinea. Argos. If Argos had remained neutral, Athens would most likely have been defeated.
The Spartans gave it a wide berth, but forgot to leave more than a token force to watch the city. The Argos militia was depleted, but as the large Spartan Army marched toward Korinthos, they did the only logical thing. That was to attack south, toward Sparta itself. Aided by a good-sized helot revolt (although many had been taken along with the campaign this time) the Argos forces attacked Sparta itself. An emergency levy militia, along with excellent Spartan discipline and fanaticism among the garrison forces, was enough to fight off the Argos assault. But a major detatchment from the army up north had to be dispatched in order to contain the attack.
The result was that two armies of equal strength met at the coming battle. Athens, watching the Argos events with amusement, took the extra time afforded to them to send military recruiters to Crete and Asia Minor (Greek portions) They returned with a lot less gold, but a lot more trained mercenaries.
So as a result, the Spartan forces had their normally stellar discipline lowered by the inclusion of helots, where the Athenian/Allied armies had their numbers and training raised by the fresh mercenaries, many former Persian Army soldiers. Granted, this lowered Athenian popularity among the citizens a bit, but no one was complaining, the assault on Athens taken into account. As the Spartans regrouped and moved toward Korinthos, the Athenian forces decided, for the first time in the war, to preemptively strike. The armies met a little east of the city.
Technically the Battle of Korinthos was a stalemate, with equal casualties on both sides. The Spartan charges were driven back with great loss. But Pericles (Commanding from the front in a manner that would be remembered epically by Thucydides) wisely decided to hold the mercenaries in reserve until the end. They proved to be particularly effective, and the helots broke at this point. Sparta was driven back to Korinthos, but they held the city. The First Battle was over.
Rapid naval communications went to Argos from the Athenian war camp, and Argos forces withdrew from their positions near Sparta. The exhausted levy forces were in no position to pursue them. Resupplying at Argos, they then moved north, effectively trapping the Spartan Army in Korinthos. The Second Battle was a failed Spartan attempt to break out south of the city, and the Third Battle of Korinthos was a devastating combined charge of the Argos and Athenian forces. The Spartan Army, formerly with no match in all Greece, was defeated. They had been besieged for a month, with little food, and the attack from both sides was too much for them. They were killed to a man, most choosing death over surrender.
The war would continue for two more years, but Sparta's end was truly at Korinthos. Their allies gone, the citizenry of Sparta itself perished in a mass suicide, followed by a burning of the city on the eve of the final allied attack.
Athens was hegemonic, and triumphant. The only question was, how long would the new Athenian Empire hold together? Pericles I may have seemed a demigod, but all mortals die eventually...
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Edit: You know, I just might do this myself. I have to extend it a little...