Year 414 BC was a year of the pre-Julian Roman calendar. At the time, it was known as the Year of the Tribunate of Cossus, Ambustus, Potitus and Albinus (or, less frequently, year 340 Ab urbe condita). The denomination 414 BC for this year has been used since the early medieval period, when the Anno Dominicalendar era became the prevalent method in Europe for naming years.
The Athenian army moves to capture Syracuse while the larger fleet of Athenian ships blocks the approach to the city from the sea. After some initial success, the Athenian troops become disorganised in the chaotic night operation and are thoroughly routed by Gylippus, the Spartan commander. The Athenian commander Lamachus is killed. Nicias, although ill, is left in sole charge of the siege of Syracuse.