Mardonius having effected this change proceeded into Europe.  He had a large land force and a powerful navy, and at first was successful both by land and sea.  The fleet took Thasos, an island valuable for its mines; and the army forced the Macedonians to exchange their position of semi-independence for that of full Persian subjects, liable to both tribute and military service.  But this fair dawn was soon overcast.  As the fleet was rounding Athos a terrible tempest arose which, destroyed 300 triremes and more than 20,000 men, some of whom were devoured by sea-monsters, while the remainder perished by drowning.  On shore, a night attack of the Brygi, a Thracian tribe dwelling in the tract between the Strymon and the Axius, brought disaster upon the land force, numbers of which were slain, while Mardonius himself received a wound.  This disgrace, indeed, was retrieved by subsequent operations, which forced the Brygi to make their submission; but the expedition found itself in no condition to advance further, and Mardonius retreated into Asia.

Darius, however, did not allow failure to turn him from his purpose.  The attack of Mardonius was followed within two years by the well-known expedition under Datis (B.C. 490), which, avoiding the dangers of Athos, sailed direct to its object, crossing the Egean by the line of the Cyclades, and falling upon Eretria and Attica.  Eretria’s punishment warned the Athenians to resist to the uttermost; and the skill of Miltiades, backed by the valor of his countrymen, gave to Athens the great victory of Marathon.  Datis fell back upon Asia, having suffered worse disasters than his predecessor, and bore to the king the melancholy tidings that his vast force of from 100,000 to 200,000 men had been met and worsted by 20,000 Athenians and Plataeans.

Still Darius was not shaken in his resolution.  He only issued fresh orders for the collection of men, ships, and materials.  For three years Asia resounded with the din of preparation; and it is probable that in the fourth year a fresh expedition would have been led into Greece, had not an important occurrence prevented it.  Egypt, always discontented with its subject position under a race which despised its religion, and perhaps occasionally persecuted it, broke out into open revolt (B.C. 487).  Darius, it seems, determined to divide his forces, and proceed simultaneously against both enemies; he even contemplated leading one of the two expeditions in person; but before his preparations were completed his vital powers failed.  He died in the year following the Egyptian revolt (B.C. 486), in the sixty-third year of his age, and the thirty-sixth of his reign, leaving his crown to his eldest son by Atossa, Xerxes.