In the summer of 429 Sparta took advantage of their superiority on land, to work on the dress - a tiny insurance policy, so valiantly fought during the Persian war, the members of the union obschegrecheskih forever pledged to defend it from aggression. Archidamus promised to respect the neutrality of Plataea, if it withdraws from the alliance with Athens and would not participate in the war. Plataeans allowed to communicate with the Athenians, who implored them not to dissolve the union and promised to help them with whatever is possible. Then Plateia Archidamus rejected the proposal, and he decided that there was sufficient justification for the assault on the city. But all attacks were repulsed the garrison of 400 Plataeans and 80 of the Athenians, which prepared food for 110 plateyskih women. The assault was stopped, and by the autumn of 429, the plateau surrounded the double wall of mud brick, which is located inside the strong garrison Peloponnesians and Boeotians. Athens did not attempt to lift the siege of the city. If they can not defend their own country, they had no hope, and to keep the plateau. On the other hand, the siege of Plataea, which lasted more than two years worth of Peloponnesians financial and human losses, which does not justify the strategic value of the city.