After the battle of Marathon the Athenians began to make preparations to resist another Persian invasion. One of their leaders, the eminent Aristides, thought that they should increase their army and meet the enemy on land. His rival, Themistocles, urged a different policy. He would sacrifice the army to the navy and make Athens the strongest sea power in Greece. The safety of Athens, he argued, lay in her ships. In order to settle the question the opposing statesmen were put to the test of ostracism. [3] The vote went against Aristides, who was obliged to withdraw into exile. Themistocles, now master of the situation, persuaded the citizens to use the revenues from some silver mines in Attica for the upbuilding of a fleet. When the Persians came, the Athenians were able to oppose them with nearly two hundred triremes [4]--the largest navy in Greece. 33. XERXES AND THE GREAT PERSIAN WAR PREPARATIONS OF PERSIA "Ten years after Marathon," says a Greek historian, "the 'barbarians' returned with the vast armament which was to enslave Hellas." [5] Darius was now dead, but his son Xerxes had determined to complete his task. Vast quantities of provisions were collected; the Hellespont was bridged with boats; and the rocky promontory of Mount Athos, where a previous fleet had suffered shipwreck, was pierced with a canal. An army of several hundred thousand men was brought together from all parts of the Great King's domain. He evidently intended to crush the Greeks by sheer weight of numbers. [Illustration: A THEMISTOCLES OSTRAKON (British Museum, London) A fragment of a potsherd found in 1897 A.D., near the Acropolis of Athens. This ostrakon was used to vote for the ostracism of Themistocles, either in 483 B.C. when he was victorious against Aristides, or some ten years later, when Themistocles was himself defeated and forced into exile.] GREEK PREPARATIONS Xerxes did not have to attack a united Greece. His mighty preparations frightened many of the Greek states into yielding, when Persian heralds came to demand "earth and water," the customary symbols of submission. Some of the other states, such as Thebes, which was jealous of Athens, and Argos, equally jealous of Sparta, did nothing to help the loyal Greeks throughout the struggle. But Athens and Sparta with their allies remained joined for resistance to the end. Upon the suggestion of Themistocles a congress of representatives from the patriotic states assembled at the isthmus of Corinth in 481 B.C. Measures of defense were taken, and Sparta was put in command of the allied fleet and army. BATTLE OF THERMOPYLAE, 480 B.C.