History of the Peloponnesian War

As for the Lacedaemonians, they had never before experienced predatory warfare of this kind, and therefore, when the Helots began to desert and there was reason to fear that the revolutionary movement might gain still further headway in their territory, they were uneasy, and, in spite of their desire not to betray their alarm to the Athenians, kept sending envoys to them in the endeavour to recover Pylos and the prisoners.

But the Athenians constantly made greater demands and the envoys, although they came again and again, were always sent home unsuccessful. Such were the events at Pylos.