Theomnestus and Apollodorus Against Neaera (102)

Then they invested the walls of Plataea with a large force, and made overtures to the Plataeans on terms that, if they would surrender their city to the Lacedaemonians, they should retain their land and enjoy their property, but that they should break off their alliance with the Athenians. The Plataeans refused this offer and made answer that they would do nothing without the Athenians, whereupon the Lacedaemonians besieged them for two years, built a double wall about their city, and made repeated assaults of every conceivable sort.