Campaigns of Alexander the Great [352-334BC]
He succeeded his father Philip II to the throne in 336 BC at the age of 20, and spent most of his ruling years conducting a lengthy military campaign throughout Western Asia and Egypt. By the age of thirty, he had created one of the largest empires in history, stretching from Greece to northwestern India. He was undefeated in battle and is widely considered to be one of history's greatest and most successful military commanders.
Alexander’s short reign marks a decisive moment in the history of Europe and Asia. His expedition and his own personal interest in scientific investigation brought many advances in the knowledge of geography and natural history. His career led to the moving of the great centres of civilization eastward and initiated the new age of the Greek territorial monarchies; it spread Hellenism in a vast colonizing wave throughout the Middle East and created, if not politically at least economically and culturally, a single world stretching from Gibraltar to the Punjab, open to trade and social intercourse and with a considerable overlay of common civilization and the Greek koinē as a lingua franca. It is not untrue to say that the Roman Empire, the spread of Christianity as a world religion, and the long centuries of Byzantium were all in some degree the fruits of Alexander’s achievement.
Alexander and his army crossed the predatory current of the Tigris River and thus overcame a natural obstacle between him and the army commanded by Darius III (Darayavas). Here, on the banks of the river, he gave his soldiers a well-deserved rest. It was the fourth year since he entered Asian soil.