Greek conquest of Persia.  All things being thus secured in his rear, Alexander, having returned into Syria, directed the march of his army, now consisting of fifty thousand veterans, eastward.  After crossing the Euphrates, he kept close to the Masian hills, to avoid the intense heat of the more southerly Mesopotamian plains; more abundant forage could also thus be procured for the cavalry.  On the left bank of the Tigris, near Arbela, he encountered the great army of eleven hundred thousand men brought up by Darius from Babylon.  The death of the Persian monarch, which soon followed the defeat he suffered, left the Macedonian general master of all the countries from the Danube to the Indus.  Eventually he extended his conquest to the Ganges.  The treasures he seized are almost beyond belief.  At Susa alone he found—­so Arrian says—­fifty thousand talents in money.

Events of the campaigns.  The modern military student cannot look upon these wonderful campaigns without admiration.  The passage of the Hellespont; the forcing of the Granicus; the winter spent in a political organization of conquered Asia Minor; the march of the right wing and centre of the army along the Syrian Mediterranean coast; the engineering difficulties overcome at the siege of Tyre; the storming of Gaza; the isolation of Persia from Greece; the absolute exclusion of her navy from the Mediterranean; the check on all her attempts at intriguing with or bribing Athenians or Spartans, heretofore so often resorted to with success; the submission of Egypt; another winter spent in the political organization of that venerable country; the convergence of the whole army from the Black and Red Seas toward the nitre- covered plains of Mesopotamia in the ensuing spring; the passage of the Euphrates fringed with its weeping- willows at the broken bridge of Thapsacus; the crossing of the Tigris; the nocturnal reconnaissance before the great and memorable battle of Arbela; the oblique movement on the field; the piercing of the enemy’s centre—­a manoeuvre destined to be repeated many centuries subsequently at Austerlitz; the energetic pursuit of the Persian monarch; these are exploits not surpassed by any soldier of later times.

A prodigious stimulus was thus given to Greek intellectual activity.  There were men who had marched with the Macedonian army from the Danube to the Nile, from the Nile to the Ganges.  They had felt the hyperborean blasts of the countries beyond the Black Sea, the simooms and sand-tempests of the Egyptian deserts.  They had seen the Pyramids which had already stood for twenty centuries, the hieroglyph-covered obelisks of Luxor, avenues of silent and mysterious sphinxes, colossi of monarchs who reigned in the morning of the world.  In the halls of Esar-haddon they had stood before the thrones of grim old Assyrian kings, guarded by winged bulls.  In Babylon there still remained its walls, once more than sixty miles in