It was during this second period that he rendered his most important services to the State and earned his greatest fame.  The dangers which threatened the Empire came from the West, and not the East.  Asia was already-subdued by Sulla, Lucullus, and Pompey, or was on the point of being subdued.  Mithridates was a formidable enemy; but he aimed at establishing an Asiatic empire, not conquering the European provinces.  He was not so dangerous as even Pyrrhus had been.  Moreover, the conquest of the East was comparatively easy,—­over worn-out races and an effete civilization; it gave eclat to Sulla and Pompey,—­as the conquest of India, with a handful of British troops, made Clive and Hastings famous; it required no remarkable military genius, nor was it necessary for the safety of Italy.  Conquest over the Oriental monarchies meant only spoliation.  It was prompted by greed and vanity more than by a sense of danger.  Pompey brought back money enough from the East to enrich all his generals, and the Senate besides,—­or rather the State, which a few aristocrats practically owned.

But the conquest of Gaul would be another affair.  It was peopled with hardy races, who cast their greedy eyes on the empire of the Romans, or on some of its provinces, and who were being pushed forward to invasion by a still braver people beyond the Rhine,—­races kindred to those Teutons whom Marius had defeated.  There was no immediate danger from the Germans; but there was ultimate danger, as proved by the union they made in the time of Marcus Antoninus for the invasion of the Roman provinces.  It was necessary to raise a barrier against their inundations.  It was also necessary to subdue the various Celtic tribes of Gaul, who were getting restless and uneasy.  There was no money in a conquest over barbarians, except so far as they could be sold into slavery; but there was danger in it.  The whole country was threatened with insurrections, leagues, and invasion, from the Alps to the ocean.  There was a confederacy of hostile kings and chieftains; they commanded innumerable forces; they controlled important posts and passes.  The Gauls had long made fixed settlements, and had built bridges and fortresses.  They were not so warlike as the Germans; but they were yet formidable enemies.  United, they were like “a volcano giving signs of approaching eruption; and at any moment, and hardly without warning, another lava stream might be poured down Venetia and Lombardy.”

To rescue the Empire from such dangers was the work of Caesar; and it was no small undertaking.  The Senate had given him unlimited power, for five years, over Gaul,—­then a terra incognita,—­an indefinite country, comprising the modern States of France, Holland, Switzerland, Belgium, and a part of Germany.  Afterward the Senate extended the governorship five years more; so difficult was the work of conquest, and so formidable were the enemies.  But it was danger which Caesar loved.  The greater