At the Battle of Thermopylae, a small force of Greek warriors led by King Leonidas of Sparta resisted the much larger Persian forces, but were ultimately defeated. According to Herodotus, the Persians broke the Spartan phalanx after a Greek man called Ephialtes betrayed his country by telling the Persians of another pass around the mountains. At Artemisium, large storms had destroyed ships from the Greek side and so the battle stopped prematurely as the Greeks received news of the defeat at Thermopylae and retreated.