The Anabasis of Alexander/Book V/Chapter IX

Alexander encamped on the bank of the Hydaspes, and Poras was seen with all his army and his large troop of elephants lining the opposite bank.^[1] He remained to guard the passage at the place where he saw Alexander had encamped; and sent guards to all the other parts of the river which were easily fordable, placing officers over each detachment, being resolved to obstruct the passage of the Macedonians. When Alexander saw this, ​he thought it advisable to move his army in various directions, to distract the attention of Porus, and render him uncertain what to do. Dividing his army into many parts, he led some of his troops now in one direction and now in another, at one time ravaging the enemy's country, at another looking out for a place where the river might appear easier for him to ford it. The rest of his troops he entrusted^[2] to his different generals, and sent them about in many directions. He also conveyed corn from all quarters into his camp from the land on this side the Hydaspes, so that it might be evident to Porus that he had, resolved to remain quiet near the bank until the water of the river subsided in the winter, and afforded him a passage in many places. As his vessels were sailing up and down the river, and skins were being filled with hay, and the whole bank appeared to be covered in one place with cavalry and in another with infantry, Porus was not allowed to keep at rest, or to bring his preparations together from all sides to any one point if he selected this as suitable for the defence of the passage. Besides at this season all the Indian rivers were flowing with swollen and turbid waters and with rapid currents; for it was the time of year when the sun is wont to turn towards the summer solstice.^[3] At this season incessant and heavy rain falls in India; and the snows on the Caucasus, whence most of the rivers have their sources, melt and swell their streams to a great degree. But in the winter they again subside, become small and clear, and are fordable in certain places, with the exception of the Indus, Ganges, and perhaps one or two others. At any rate the Hydaspes becomes fordable.