Early in his enterprise, which is to say at a time when a failure could overturn him, he left little to chance ; when fortune placed him above events, temerity was sometimes one of his means. When before his departure he marches against the Triballians and the Illyrians, you see a war like the one Cæser since waged in the Gauls. When he is back in Greece, it is as if despite himself that he takes and destroys Thebes : camped near their city, he waits for the Thebans to sue for peace ; they precipitate their own ruin. When it comes to fighting the Persians’ marine, it is rather Parmenion who shows audacity ; it is rather Alexander who shows wisdom. It was his contrivance to separate the Persians from the seashore and reduce them to abandoning their own navy, in which they were superior. Tyre was, in principle, attached to the Persians, who could not do without its trade and its marine : Alexander destroyed it. He took Egypt, which Darius had left void of troops, while he was assembling armies without number in another theatre.
With the crossing of the Granicus, Alexander became master of the Greek colonies ; the battle of Issus gave him Tyre and Egypt ; the battle of Arbela gave him the entire world.
After the battle of Issus, he allows Darius to flee, and turns his attention to consolidating and managing his conquests ; after the battle of Arbela, he follows him so closely that he leaves him no retreat anywhere in his empire. Darius enters his cities and provinces only to leave them again ; Alexander’s marches are so rapid that you think you are seeing universal domination rather as the prize for the race, as in the Greek games, than the prize for victory.
This is how he made his conquests ; let us see how he preserved them.