Returning to Patala, he found that the citadel had been fortified and that Peithon had arrived with his army, having accomplished everything for which he was despatched. He ordered Hephaestion to prepare what was needful for the fortification of a naval station and the construction of dockyards; for he resolved to leave behind here a fleet of many ships near the city of Patala, where the river Indus divides itself into two streams. He himself sailed down again into the Great Sea by the other mouth of the Indus, to ascertain which branch of the river is easier to navigate. The mouths of the river Indus are about 1800 stades distant from each other.[779] In the voyage down he arrived at a large lake in the mouth of the river, which the river makes by spreading itself out; or perhaps the waters of the surrounding district draining into it make it large, so that it very much resembles a gulf of the sea.[780] For in it were seen fish like those in the sea, larger indeed than those in our sea. Having moored his ships then in this lake, where the pilots directed, he left there most of the soldiers and all the boats with Leonnatus; but he himself with the thirty-oared galleys and the vessels with one and a half row of oars passed beyond the mouth of the Indus, and advancing into the sea also this way, ascertained that the outlet of the river on this side (_i.e._ the west) was easier to navigate than the other. He moored his ships near the shore, and taking with him some of the cavalry went along the sea-coast three days’ journey, exploring what kind of country it was for a coasting voyage, and ordering wells to be dug, so that the sailors might have water to drink. He then returned to the ships and sailed back to Patala; but he sent a part of his army along the sea-coast to effect the same thing, instructing them to return to Patala when they had dug the wells. Sailing again down to the lake, he there constructed another harbour and dockyard; and leaving a garrison for the place, he collected sufficient food to supply the army for four months, as well as whatever else he could procure for the coasting voyage. CHAPTER XXI. CAMPAIGN AGAINST THE ORITIANS.