There were three. I was talking about the First, Xerxes's father
I hope you know that the Ionian Revolt was suspressed first before he invaded Greece and FAILED!
http://en.wikipedia.org/wiki/Darius_the_Great
"At the time, European Greece was intimately connected with the Greek cities on the coast of Asia Minor and as a result
Athens and
Eretria gave support to the
Ionian Revolt against the Persians. Once the rebellion was put down, the Persians attempted to punish Athens and European Greece for meddling in the rebellion. But the first expedition, that of
Mardonius, failed on the cliffs of
Mount Athos (492 BC), and the army which was led into
Attica by
Datis in 490 BC was beaten at the
Battle of Marathon. Before Darius had finished his preparations for a third expedition an
insurrection broke out in Egypt (486 BC). In the next year Darius died, probably in October
485 BC, after a reign of thirty-six years."
The Third expedition was when Xerxes invaded Greece and Ultimately FAILED as his Father did 10 years before!
http://en.wikipedia.org/wiki/Xerxes_I_of_Persia
Invasion of the Greek mainland
Main article: Greco-Persian Wars
Darius left to his son the task of punishing the
Athenians,
Naxians, and
Eretrians for their interference in the
Ionian revolt and their defeat of the Persians at
Marathon. From
483 Xerxes prepared his expedition with great care: a channel was dug through the
isthmus of the peninsula of
Mount Athos, provisions were stored in the stations on the road through
Thrace, two bridges were thrown across the
Hellespont. According to
Herodotus, Xerxes' first attempt to bridge the Hellespont ended in failure when a storm destroyed the
flax and
papyrus bridge; Xerxes ordered the Hellespont whipped three hundred times and had
fetters thrown in. Xerxes' second attempt to bridge the Hellespont was successful.
[3] Xerxes concluded an alliance with
Carthage, and thus deprived
Greece of the support of the powerful monarchs of
Syracuse and
Agrigentum. Many smaller Greek states, moreover, took the side of the Persians, especially
Thessaly,
Thebes, and
Argos. Xerxes, with a large fleet and army (
Herodotus the Greek historian claimed that there were over 2,000,000 soldiers), set out in the spring of
480 from
Sardis. Xerxes was victorious during the initial battles, but at the
Battle of Thermopylae, a small force of warriors, led by King
Leonidas, resisted the much larger Persian forces. The Greeks were defeated by Xerxes army, though at a great cost to the Persians, thus resulting in a
pyrrhic victory for the Persians. After Thermopylae,
Athens was conquered, the Athenians and Spartans were driven back to their last line of defense at the
Isthmus of Corinth and in the
Saronic Gulf. At Artemisium the battle was indecisive as large storms destroyed ships from both sides. The battle was also stopped prematurely as the Greeks caught news of the defeat at Thermopylae and retreated. But Xerxes was induced by the astute message of
Themistocles (against the advice of
Artemisia of
Halicarnassus) to attack the Greek fleet under unfavourable conditions, instead of sending a part of his ships to the
Peloponnesus and awaiting the dissolution of the Greek armament. The
Battle of Salamis (
September 29,
480) was won by the Athenians. Having lost his communication by sea with
Asia, Xerxes was forced to retire to Sardis; the army he left in Greece under
Mardonius was beaten in
479 B.C. at
Plataea. The defeat of the Persians at
Mycale roused the Greek cities of Asia.