Anxious to get possession of this place before the actual outbreak of the war which they saw to be inevitable, the Thebans planned its surprise and capture. Three hundred Thebans gained access to the unguarded city in the dead of night, and marching to the public square, summoned the Platæans to exchange the Athenian for a Boeotian alliance. The Platæans were upon the point of acceding to all the demands made upon them, when, discovering the small number of the enemy, they attacked and overpowered them in the darkness, and took a hundred and eighty of them prisoners. These captives they afterwards murdered, in violation, as the Thebans always maintained, of a sacred promise that their lives should be spared. This wretched affair at Platæa precipitated the war (431 B.C.). INVASION OF ATTICA: PESTILENCE AT ATHENS.--A Spartan army was soon overrunning Attica, while an Athenian fleet was ravaging the coasts of the Peloponnesus. Pericles persuaded the country people of Attica to abandon their villas and hamlets and gather within the defences of the city. He did not deem it prudent to risk a battle in the open fields. From the walls of Athens the people could see the flames of their burning villages and farmhouses, as the enemy ravaged the plains of Attica up to the very gates of the city. It required all the persuasion of Pericles to restrain them from issuing in a body from behind the ramparts and rushing to the defence of their homes. The second year the Lacedæmonians again ravaged the fields about Athens, and drove the Athenians almost to frenzy with the sight of the flame and smoke of such property as had escaped the destruction of the previous year. To increase their misery, a pestilence broke out within the crowded city, and added its horrors to the already unbearable calamities of war. No pen could picture the despair and gloom that settled over the city. Athens lost, probably, one-fourth of her fighting men. Pericles, who had been the very soul and life of Athens through these dark days, fell a victim to the plague (429 B.C.). In dying, he said he considered his greatest praise to be that "he had never caused an Athenian to put on mourning." After the death of Pericles the leadership of affairs at Athens fell into the hands of unprincipled demagogues, of whom Cleon was chief. The mob element got control of the popular assembly, so that hereafter we shall find many of its actions characterized neither by virtue nor wisdom. DESPERATE AND CRUEL CHARACTER OF THE WAR.--On both sides the war was waged with the utmost vindictiveness and cruelty. As a rule, all the men captured by either side were killed.