Battle of Megara

Location
The city of Megara was situated in the country of Megarid, between central Greece and the Peloponnese. Megara, ally of Sparta, consisted of farming villages, with flat plains and foothills. Megara hosted two harbors: Pagae (modern Alepochori-Corinthian Gulf) and Nisaia (Saronic Gulf), making it a prime focus of contention1.

The Athenian Threat
Attica had been under siege by the Peloponnesian army led by Spartan King Archidamus. The land siege kept Athenians stuck in their city. However, with the Peloponnesian withdrawal, Athens began to attack2. Starting as early as 431 BC, Megara was under consistent attack from Athens. During the first invasion Athens brought 10,000 Athenians and numerous allies.

Athens then set up a fort on Salamis (near Nisaia), and created shipping blockades. The blockades delayed import of food and supplies to Megara. Megarians still had control of Pagae, but Megara was effectively isolated from the western food supplies. Unable to produce normal proportions of food, the situation was dire for the Megarians.

Megarian Oligarchy
Urged by the Megarian Oligarchy in 429, the Peloponnesian fleet attacked the Athenian fort at Salamis. Unknown to the Peloponnesians, the attack was revealed to Athens by beacon lights. Athens dispatched a fleet from the Athenian port of Piraeus. The Peloponnesian attack was abandoned due to the Megarian ships being in a state of disrepair.

Under the rule of the Pro-Spartan and Pro-Corinthian Oligarchy, Megara lost the port city of Minoa to Athens in 427. This loss was a contributing factor to further civil unrest. Megarian revolutions against the Oligarchy began shortly after and Megara became a Democratic state.

The Megarian Oligarchy were exiled. Many exiles were permitted by Sparta to inhabit the Boeotian town of Plataea for a year2. Boeotia separated Megara and Athens with high mountains ranges in the north1. The Spartans were then able to prevent interactions between Megarian Democrats and Athenians on Minoa2.

The exiled Megarians in Plataea, began northern raids in Megarid, and took Pagae. With Oligarch sympathizers still in Megara, the Oligarchs returned to Megara in 427 BC, and Democracy collapsed.

The Spartan Role
It is suspected that Athens prevented food supplies in order to gain control of Megara and prevent further invasions of Attica by the Peloponnesians. However, Athens' capture of Pylos in 425 detained the Peloponnesian army in Messenia, which lessened the importance of Megara to Athenians. Athens had also successfully trapped hundreds of Spartans on Sphacteria. The Spartans removed all military forces from Messina and arranged a truce. Ambassadors were sent to Athens without consulting Spartan allies. Athens had extensive demands, and Sparta requested a private discussion.

Spartan allies were uneasy with the scenario. Megara had a distrust of the Spartans since the Revolution. Megarians were concerned that Sparta may turn over Nisaia to the Athenians. Meanwhile, within the walls of Megara, the Democrats planned to aid Athens in capturing the long walls of Nisaia. Athens then discredited the Spartan embassy because of their request for privacy, and the truce failed.

The Battle Commences
During the night Athenians and their allies approached Megara from Minoa and the road to Eleusis. The plan worked and the Peloponnesian garrison was effectively isolated from the city. As morning came, Megarian Democrats pretended to be outraged by the captured walls. The Democrats encouraged Megarians to open the city gates and attack the Athenians. The Democrats then decorated themselves with oil to be easily distinguished from other Megarians. At the crucial moment, the plot was uncovered by the Oligarchs, and the gate remained closed.

Athens sensed the change of plan and attacked the Nisaia garrison. Spartans were taken as prisoners and the Peloponnesians were allowed to ransom themselves. Spartan Commander Brasidas appeared with an army larger than the Athenians. The two cavalries fought under the walls of Megara.

Resolution
The Battle of Megara was fought in 424 BC between Athens and Megara, an ally of Sparta. The Athenians were repelled.

The Oligarchs opened the gate to Brasidas and their allies. The Athenians declined to battle with the Peloponnesians. Over time, Brasidas and Athens both left the city. The Peloponnesian armies stayed.