A few years after Cimon was ostracized, the Athenians faced a minor war at Tanagra. Tanagra was a minor city barely outside Attica. The Spartans had sent an army there and, obviously, the Athenians couldn't afford to have a Spartan force sitting alongside their border like that. The Athenians assembled their army and marched off to beat up the Spartans.
The two armies duly assembled in their lines outside Tanagra, and faced each other, ready to commence the battle, when who should show up but Cimon.
Now Cimon was ostracized, which meant exiled from Attica for 10 years on pain of death. But Tanagra was outside Attica, so Cimon had every right to turn up for the battle. Cimon stepped into the Athenian line, intending to fight as a common soldier.
Suddenly Pericles had a problem. Cimon was the arch-enemy of Pericles in politics, and Cimon was a great soldier. If Cimon displayed outstanding valour in the coming fight, the fickle Athenians might invite him back.
Pericles demanded Cimon go away.
Cimon pointed out he had every right to be there. Cimon also had an underlying motive: Cimon's ostracism had been for excessive friendliness with Sparta. If Cimon, in full view of his fellow Athenians, slaughtered a few Spartans it would give the lie to the indictments against him.
Pericles knew this perfectly well. He insisted that Cimon go away.
Things got a teensy bit violent, which is liable to happen when everyone involved in an argument is wearing armour and carrying spears and swords.
The Spartans stood and watched in bemusement while their enemy the Athenians began hacking away at each other. The friends of Pericles were determined to drive away Cimon. The friends of Cimon were equally determined he should remain.
Cimon was eventually forced from the field, after which the officially scheduled battle could commence.
Nicolaos will, of course, find himself stuck in the middle of this debacle. It can't appear for many books down the road, but I'm really looking forward to writing this scene.