Pissuthnes had been the satrap of Lydia for at least two decades when he decided to revolt against king Darius II Nothus in 420 BCE. The reason for this revolt is not recorded. What is certain, however, is that he was able to recruit mercenaries from Greece, where the Archidamian War (431-421) had just come to an end. The great king now sent a Persian nobleman named Tissaphernes to Lydia, with a special assignment to incite a rebellion among the mercenaries. He was successful, and once he had robbed Pissuthnes from their support, he offered negotiations, and arrested the rebel when he arrived at the appointment (415). Darius had the man executed.
This, however, was not the end of the trouble, because Pissuthnes' bastard son Amorges continued the insurrection from Caria, where he occupied the port of Iasus (between Miletus and Halicarnassus). Like his father, who had received help from an Athenian officer named Lycon, Amorges was supported by the Athenians. Their ships were regular visitors of Iasus. An Athenian inscription mentioning a payment to a general in Ephesus may refer to this support as well.
Tissaphernes had orders to get rid of Amorges. However, the rebel had Greek mercenaries (probably Arcadians or Argives) at his disposal, and as long as Athens ruled the waves, a siege of Iasus was impossible. That changed in 413, when the Athenians suffered a catastrophic defeat on Sicily, which they had tried to conquer. The Spartans now resumed the Peloponnesian War. (To distinguish it from the Archidamian War, the second part is usually called Decelean or Ionian War; 413-404). Tissaphernes offered support to the Spartans, and in 412, a treaty was concluded. One of its terms was that "if anyone revolts from the King, he shall be the enemy of the Spartans as well". This was almost certainly directed against Amorges.
The Spartans did what they were supposed to do. In the winter of 412/411, they sailed to Iasus. The inhabitants saw the ships approaching and, thinking they belonged to the Athenian navy, let them in. When the Iasians discovered whom they had welcomed, it was too late, and Amorges was arrested. He was handed over to Tissaphernes, and Amorges' Peloponnesian mercenaries switched sides.
This was the end of the affair. When the Spartan-Persian treaty was renewed, Tissaphernes no longer demanded Spartan support for war against rebels. The Athenian commander who should have been able to prevent this from happening, Phrynichus, was later accused of treason.
The Athenian assistance to Amorges was probably decisive in the Peloponnesian War. In his speech On the peace, the Athenian orator Andocides claimed that it was precisely this support that had caused the Persian king to support Sparta and interfere in the Peloponnesian War against Athens (text).