The fact is that the Greeks, as a very enterprising and active race, came into frequent collision with their Eastern neighbours. We catch glimpses of this in very remote times. To these, however, we need not go back. Towards the end of the eighth or early in the seventh century B.C., the kings of Lydia began to encroach on their Greek neighbours and conquered city after city. Crœsus, who was the last of the dynasty, had made himself master of all of them before he was himself overthrown by Cyrus the Persian. This event meant nothing for the Greeks but a change of masters, and this was not a change for the better. Lydians and Greeks had long been neighbours, and could contrive to live on tolerable terms. The Persians were strangers from a remote country, and were of a harsher temper. In 502 B.C. a general rebellion took place, in the course of which Sardis, the local capital of the Persians, was burnt. A contingent of Athenian troops took part in this affair, and their presence was the immediate cause of the great struggle that followed. The war between Greece and Persia lasted, with intervals of doubtful peace, something less than 180 years. The first great conflict was at Marathon. In the late summer of 490 B.C. the Persian army landed at the Bay of Marathon, distant from Athens about twenty miles as the crow flies, about twenty-five by the only road practicable for wheeled conveyances. Of the Persian numbers we know nothing. Herodotus, who is our best authority (born in 480, he probably talked with men who had fought in the battle), gives no figures. Later writers speak of impossible numbers, 600,000 being the largest, 110,000 the smallest estimate. To carry even 110,000 across the Ægean sea would have been a heavy task. If a guess has to be made, one may venture to say 60,000. The Athenians numbered 10,000, and they had with them 1,000 men from Platæa, a little Bœotian town, which they had recently taken under their protection. The Plain of Marathon is about six miles long from south-west to north-east, and in breadth varies from two and a half to one and a-half miles. On the north-east it is bounded by a great marsh, which is divided from the sea by a narrow slip of land. There is another smaller marsh on the south-west. Along the edge of this swamp ran the road to Athens. It was probably the immediate object of Datis, the Persian general, to seize this road, and of the Athenian commanders to protect it. Their right wing rested on the seaward slope of what is now called Agrieliki, the north-eastern spur of Pentelicus. About a mile from this may still be seen the remains of the mound which was raised over the bones of the Athenians slain in the battle. It is probable that this marks the spot where the fight raged most fiercely. If this is so, the Persian lines must have been advanced to within a short distance of the rising ground.