The battle of Tanagra (426 BC) was a minor Athenian victory won close to the city of Tanagra in Boeotia. Tanagra was located close to the border between Attica and Boeotia, and had been the site of a battle during the First Peloponnesian War. This second battle of Tanagra came at the end of an otherwise unsuccessful Athenian naval expedition during the Great Peloponnesian War. A fleet of sixty ships carrying 2,000 hoplites and commanded by Nicias, son of Niceratus, was sent to attack the island of Melos, to the south-east of Athens.
Melos had never been part of the Athenian Empire, and had no intention of joining now. The Athenian troops landed on the island and laid the country waste, but the Melians refused to come to terms. The Athenian fleet then sailed back to the north-west, around the northern coast of Attica, and landing at Oropus, at the northern edge of Attica. The Athenians then marched to the area of Tanagra, where they met up with the main army from Athens, responding to a prearranged signal. This army was commanded by Hipponicus son of Callias and Eurymedon son of Thucles.
The combined Athenian army spent one day devastating the countryside around Tanagra, presumably in the hope that this would bring on a battle. If this was the plan then it was successful. On the following day an army came out of Tanagra, most made up of local troops, but with a contingent from Thebes. The two sides clashed somewhere near the city, and the Athenians were victorious. They erected a trophy to commemorate the victory, and the army then split up. The contingent from Athens returned to the city, while the fleet moved north-west along the coast to devastate Locris before also returning to Athens.