Overview
405 BC is a retrospective chronological label used in modern histories to identify events near the end of the Peloponnesian War. In the Roman world the year fell within the pre-Julian Roman calendar; for more on that system see contemporary Roman dating. Different peoples in the ancient Mediterranean and beyond used other dating systems, so the single label "405 BC" is a convenience for modern readers.
Major events
The year is best known for a decisive naval engagement in the Hellespont region that gravely weakened Athenian sea power. Spartan forces under the command of Lysander achieved a crushing victory over the Athenian fleet, an outcome that permitted Sparta to control grain routes and to blockade Athens. This defeat precipitated the final collapse of Athenian resistance in the following year.
- Decisive Spartan naval victory in the Hellespont region (Battle of Aegospotami).
- Spartan control of key maritime supply lines to Athens and the beginning of an effective blockade.
- Political instability in the Aegean as allied cities reacted to shifting power.
Political consequences and aftermath
The military reversal in 405 BC set the stage for the surrender of Athens in 404 BC and the brief imposition of an oligarchic regime in the city. For Sparta the victory secured a period of hegemony over many Greek states, although that dominance proved temporary in the decades that followed as other powers, notably Thebes and later Macedon, reshaped the Greek world.
Sources and historiography
Our knowledge of events around 405 BC comes through a mix of ancient historians and later traditions. Narrative accounts are preserved in works by authors who continued or summarized the contemporary histories of the Peloponnesian War. Modern reconstructions rely on those literary texts together with archaeological evidence; historians treat details such as troop numbers and exact sequences with caution where the ancient evidence is uneven or partisan.
Significance: Although the year-numbering "405 BC" is a later convention, the events clustered in this period mark a turning point in classical Greek history, signaling the end of Athenian maritime supremacy and initiating a new phase of interstate rivalry across the eastern Mediterranean.