Near Patala the stream of the Indus is divided into two large rivers,[183] both of which retain the name of the Indus till they enter the sea. Here Alexander set about the construction of a roadstead and dock, and when some satisfactory progress had been made with these undertakings, he resolved to sail down to the mouth of the right arm of the river.[184] To Leonnatos he gave the command of about 1000 cavalry and 8000 heavy and light infantry, and despatched him to move down the island of Patala, holding along the shore in a line with the squadron of ships. He set out himself on a voyage down the right arm of the river, taking with him the fastest vessels with one and a half bank of oars, all the thirty-oared galleys, and several of the smaller craft. As the Indians of that region had fled, he had no pilot to direct his course, and this made the navigation all the more difficult. Then on the second day after he had started a storm arose, and the gale blowing against the current made deep furrows in the river, and battered the hulls of the vessels so violently that most of his ships were damaged, while some of the thirty-oared galleys were completely wrecked, though the sailors managed to run them on shore before they went all to pieces in the water. Other vessels were therefore constructed; and Alexander, having despatched the quickest of the light-armed troops some distance into the interior, captured some Indians, whom he employed in piloting his fleet for the rest of the voyage. But when they found themselves where the river expands to the vast breadth of 200 stadia the wind blew strong from the outer sea, and the oars could scarcely be raised in the swell. They therefore again drew toward the shore for refuge, and the fleet was steered by the pilots into the mouth of a canal. _Chapter XIX.—The fleet is damaged by the tide, halts at an island in the Indus, and thence reaches the open sea_