[333] Thucyd. ii, 78; iii, 21. From this description of the double wall and covered quarters provided for what was foreknown as a long blockade, we may understand the sufferings of the Athenian troops (who probably had no double wall), in the two years’ blockade of Potidæa,—and their readiness to grant an easy capitulation to the besieged: see a few pages above. At the same time that Archidamus began the siege of Platæa, the Athenians on their side despatched a force of two thousand hoplites and two hundred horsemen, to the Chalkidic peninsula, under Xenophon son of Euripidês (with two colleagues), the same who had granted so recently the capitulation of Potidæa. It was necessary doubtless, to convoy and establish the new colonists who were about to occupy the deserted site of Potidæa: moreover, the general had acquired some knowledge of the position and parties of the Chalkidic towns, and hoped to be able to act against them with effect. They first invaded the territory belonging to the Bottiæan town of Spartôlus, not without hopes that the city itself would be betrayed to them by intelligences within: but this was prevented by the arrival of an additional force from Olynthus, partly hoplites, partly peltasts. These peltasts, a species of troops between heavy-armed and light-armed, furnished with a pelta (or light shield), and short spear, or javelin, appear to have taken their rise among these Chalkidic Greeks, being equipped in a manner half Greek and half Thracian: we shall find them hereafter much improved and turned to account by some of the ablest Grecian generals. The Chalkidic hoplites are generally of inferior merit: on the other hand, their cavalry and their peltasts are very good: in the action which now took place under the walls of Spartôlus, the Athenian hoplites defeated those of the enemy, but their cavalry and their light troops were completely worsted by the Chalkidic. These latter, still farther strengthened by the arrival of fresh peltasts from Olynthus, ventured even to attack the Athenian hoplites, who thought it prudent to fall back upon the two companies left in reserve to guard the baggage. During this retreat they were harassed by the Chalkidic horse and light-armed, who retired when the Athenians turned upon them, but attacked them on all sides when on their march; and employed missiles so effectively that the retreating hoplites could no longer maintain a steady order, but took to flight, and sought refuge at Potidæa. Four hundred and thirty hoplites, near one-fourth of the whole force, together with all three generals, perished in this defeat, and the expedition returned in dishonor to Athens.[334] [334] Thucyd. ii, 79.