Meanwhile the counterwall was advancing steadily up the hill, and every day Gylippus drew up his army, to cover the operations of the workmen. At last he determined to force on an engagement, and in the first encounter the Syracusans, fighting in a confined space, which prevented their cavalry from coming into action, suffered a defeat. In no wise discouraged by this reverse, on the next day they took up a position in the more open ground, and offered battle again. By this time the Syracusan counterwork had almost passed the end of the Athenian wall, and if it were carried a few yards further, the siege of Syracuse would be brought to a standstill. Roused by the imminence of the crisis, Nicias determined to make one more effort to regain his mastery in the field, and led his troops to the attack. The main body of the hoplites were soon hotly engaged on both sides, and in the midst of the action Gylippus directed his cavalry and light-armed infantry to make a sudden charge on the Athenian left. This movement was executed with so much skill and resolution that the Athenians in that part of the line gave way, and drew after them the rest of their comrades, who broke their ranks, and fled for shelter behind the siege works.
The Syracusans lost no time in turning their victory to account. On the very same night their wall was extended some distance beyond the blockading line, and until this new barrier was overthrown, the investment of Syracuse had now become impossible.
Whichever way he looked, Nicias saw himself menaced with failure and defeat. He had sent twenty ships to intercept the Corinthian squadron on its voyage from Leucas; but the little fleet of rescue succeeded in avoiding the snare, and made its way into the port of Syracuse, thus adding twelve fresh vessels to the defending force. Gylippus himself was marching unhindered up and down the island, passing from city to city, and raising reinforcements of ships and men; and a second embassy had been despatched by the Syracusans, to carry the news of their victory to Corinth and Sparta, and ask for further help. Another ominous sign of coming events was the bustle and activity now visible in the dockyards of Syracuse and the waters of the Little Harbour; for the Syracusans had turned their attention seriously to their fleet, and thought of nothing less than attacking the Athenians on their own element.