With the development of a naval science rose also a naval profession. At Salamis Themistocles was a politician and Eurybiades was a soldier; it happened that they were made fleet commanders for the emergency. Phormio was a naval officer by profession, and he won by genius combined with superior efficiency in the personnel under his command. In his courage, resourcefulness, in the spirit he inspired, and the high pitch of skill he developed among his officers and men, he is an ideal type for every later age. Little is known of his life and character beyond the story of these two exploits, but they are sufficient to give him the name of the first great admiral of history. His exploits illustrate, too, at the very outset of naval history, the vital truth that the man counts more than the machine. In these later days, when the tendency is to measure naval power merely by counting dreadnoughts, and to settle all hypothetical combats by the proportion of strength at a given point on the game board, it is well to remember that the most overwhelming victories have been won by the skill and audacity of a great leader, which overcame odds that would be reckoned by the experts as insuperable. The Peloponnesian war dragged on with varying fortunes for ten years. The Athenians were regularly successful on the sea and unsuccessful on land. They seem to have laid an unwise dependence on their navy for a state situated on the mainland with land communications open to the enemy. They attempted to make an island of their state by withdrawing into the city of Athens the entire population of Attica, leaving open to the invader the rest of the province. The repeated ravaging of Attica by Peloponnesian armies weakened both the resources and the morale of the Athenians, and the crowding of the inhabitants into the city resulted in frightful mortality from the plague. At the same time the naval expeditions sent out to harry the coast of the Peloponnesus accomplished nothing of real advantage. In 421 a truce was agreed upon between Athens and Sparta, which was to last fifty years. Both sides were sorely weakened by the protracted struggle and neither had gained any real advantage over the other. Without waiting to recuperate from the losses of the war, Athens embarked in 415 on an ambitious plan of conquering Syracuse, and gaining all of Sicily as an Athenian colony. In the event of success Athens would have a western outpost for the eventual control of the Mediterranean, as she already had an eastern outpost in Ionia, which gave her control of the AEgean.