Megara, an ally of Sparta, consisted of farming villages, with flat plains and foothills, and hosted two harbors: Pagae (modern Alepochori-Corinthian Gulf) and Nisaia (Saronic Gulf), making it a prime focus of contention1.
Attica had been under siege by the Peloponnesian army led by the Spartan king, Archidamus II.
Athens then set up a fort on Salamis, near Nisaia, and created shipping blockades.
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 in Megara began to become dire.
Urged by the Megarian oligarchy in 429, the Peloponnesian fleet attacked the Athenian fort at Salamis.
Under the rule of the pro-Spartan and pro-Corinthian oligarchy, Megara lost the port city of Minoa to Athens in 427, was a contributing factor in more civil unrest.
The exiled Megarians in Plataea, began northern raids in Megarid and took Pagae.
However, Athens' capture of Pylos in 425 detained the Peloponnesian army in Messenia, which lessened the importance of Megara to Athenians.
During the night, Athenians and their allies approached Megara from Minoa and the road to Eleusis.
At the crucial moment, the plot was uncovered by the Oligarchs, and the gate remained closed.
Rhetorically, Brasidas was able to employ the memory of Athenian hesitance in Megara to great effect during his remaining campaigns.