Darius died while in the process of preparing a second army to invade the Greek mainland, leaving to his son the task of punishing the Athenians, Naxians, and Eretrians for their interference in the Ionian Revolt, the burning of Sardis, and their victory over the Persians at Marathon. From 483 BC, Xerxes prepared his expedition: The Xerxes Canal was dug through the isthmus of the peninsula of Mount Athos, provisions were stored in the stations on the road through Thrace, and two pontoon bridges later known as Xerxes' Pontoon Bridges were built across the Hellespont. Soldiers of many nationalities served in the armies of Xerxes from all over his multi-ethnic massive Eurasian-sized empire and beyond, including the Assyrians, Phoenicians, Babylonians, Egyptians, Jews, Macedonians, European Thracians, Paeonians, Achaean Greeks, Ionians, Aegean islanders, Aeolians, Greeks from Pontus, Colchians, Indians and many more.