The Medes had, it is probable, been for some time growing in strength, owing to the recent arrival in their country of fresh immigrants from the far East.  Discarding the old system of separate government and village autonomy, they had joined together and placed themselves under a single monarch; and about the year B.C. 634, when Asshur-bani-pal had been king for thirty-four years, they felt themselves sufficiently strong to undertake an expedition against Nineveh.  Their first attack, however, failed utterly.  Phraortes, or whoever may have been the real leader of the invading army, was completely defeated by the Assyrians; his forces were cut to pieces, and he himself was among the slain.  Still, the very fact that the Medes could now take the offensive and attack Assyria was novel and alarming; it showed a new condition of things in these parts, and foreboded no good to the power which was evidently on the decline and in danger of losing its preponderance.  An enterprising warrior would doubtless have followed up the defeat of the invader by attacking him in his own country before he could recover from the severe blow dealt him; but the aged Assyrian monarch appears to have been content with repelling his foe, and made no effort to retaliate.  Cgaxares, the successor of the slain Median king, effected at his leisure such arrangements as he thought necessary before repeating his predecessor’s attempt.  When they were completed—­perhaps in B.C. 632—­he led his troops into Assyria, defeated the Assyrian forces in the field, and, following up his advantage, appeared before Nineveh and closely invested the town.  Nineveh would perhaps have fallen in this year; but suddenly and unexpectedly a strange event recalled the Median monarch to his own country, where a danger threatened him previously unknown in Western Asia.

When at the present day we take a general survey of the world’s past history, we see that, by a species of fatality—­by a law, that is, whose workings we cannot trace—­there issue from time to time out of the frozen bosons of the North vast hordes of uncouth savages—­brave, hungry, countless—­who swarm into the fairer southern regions determinedly, irresistibly; like locusts winging their flight into a green land.  How such multitudes come to be propagated in countries where life is with difficulty sustained, we do not know; why the impulse suddenly seizes them to quit their old haunts and move steadily in a given direction, we cannot say:  but we see that the phenomenon is one of constant recurrence, and we therefore now scarcely regard it as being curious or strange at all.  In Asia.  Cimmerians, Scythians, Parthians, Mongols, Turks; in Europe, Gauls, Goths, Huns, Avars, Vandals, Burgundians, Lombards, Bulgarians, have successively illustrated the law, and made us familiar with its operation.  But there was a time in history before the law had come into force; and its very existence must have been then unsuspected.  Even since it began to operate, it has so often undergone prolonged suspension, that the wisest may be excused if, under such circumstances, they cease to bear it in mind, and are as much startled when a fresh illustration of it occurs, as if the like had never happened before.  Probably there is seldom an occasion of its coming into play which does not take men more or less by surprise, and rivet their attention by its seeming strangeness and real unexpectedness.