Archelaus, a son of Perdiccas II of…

Ephesus shares in the general revolt of 412 BCE against Athens: siding with Sparta, and will remain an effective ally of Sparta down to the end of the war.

Miletus, too, sides with Sparta against Athens, as do …

…the Cnidians, who had earlier supported Athens in the Delian League against Persia.

Tissaphernes' forces have conquered most of Ionia by year's end.

Alcibiades had helped stir up revolt among Athenian allies in Ionia, but Sparta now turns against him, and he moves to Sardis to exercise his charm on the Persian governor.

The outbreak of an unknown disease causes a food shortage in the Roman Republic in 412 BCE and a famine is only prevented with food relief from Sicily and Etruria, and via trade missions to the "peoples round about who dwelt on the Tuscan sea or by the Tiber."

Hippocrates names a wide variety of symptoms, among them: fever, coughing, pain in head and neck, and emaciation.

The year-long epidemic disease, possibly influenza, proves fatal most often among prepubescent children.

Chios also revolts, and is ravaged by Athens in reprisal.

Archelaus, almost immediately after he takes power, is faced with a situation that allows him to completely reverse Macedon's relationship with Athens, which has been a major threat for the past half century.

The Athenians had experienced a crushing defeat at Syracuse in late 413 during which most of their ships were destroyed.

This leaves the Athenians in desperate need of a huge amount of timber to build new ships and Archelaus in a position to set the price.

Archelaus generously supplies the Athenians with the timber they need.

In recognition of this, the Athenians honor Archelaus and his children with the titles of proxenos and euergetes.

Euripides, continuing in a subversive vein with Helen, his 412 BCE production, further domesticates myth, mocks the gods, and has his human characters behaving in irrational ways.

Athens, in a near-miraculous recovery from its defeats in Sicily, manages in 412 BCE to rebuild its navy and recover some rebellious states.

This military resilience is remarkable, but the political credibility of the radical democracy has been battered: the rich have lost money, the thetes have lost men, all classes have lost their illusions.

This is a situation ripe for exploitation by intellectual activists, who dislike the democracy anyway.

Sparta makes peace with the Persians in 411 BCE, recognizing Persia's claims to the Ionian cities.

Persia begins helping Sparta to build a navy.

The Persian money given to Sparta is hardly lavish, and the fleet does not materialize at all (perhaps, as Thucydides hints, because Tissaphernes wants to wear down both sides, but perhaps because it is needed for use against Egypt, where there is papyrus evidence for a revolt from Persian authority at this time).