The actual crossing of the division under his command was done under his own eyes. Regiments of heavy-armed men were left on the right bank in anticipation of a possible rear attack by Abisares, prince of Cashmir, who, it was known, had promised to assist Porus in resisting the invading army. The passage was facilitated by the stormy weather which prevailed during the night. The Indian outposts heard nothing, and Alexander led the way safely past the island to the opposite shore, where, though some difficulty was caused by mistaking an islet for the mainland, the cavalry were disembarked and put in battle array. The whole number of troops under Alexander’s command were 6000 hypaspists, 4000 light-armed foot, 5000 cavalry, including 1000 Scythian archers. In the meantime the Indian outposts had ridden away to announce to Porus what had happened and to prepare him for the news of the Greek advance. Alexander went swiftly forward, taking with him all the cavalry, and he soon met and defeated a detachment of 1000 Indian horsemen and 160 chariots under the command of the son of Porus. The Indian king himself was advancing with the bulk of his army, and he drew up his line of battle as soon as he found a piece of sandy ground suitable for displaying the cavalry and elephants. In front he placed 200 elephants at intervals of 100 feet, and behind them his infantry to the number of 20,000. In the wings his cavalry were drawn up, about 4000 in all. Alexander placed the pick of his army, the hypaspists, immediately in front of the elephants. The use of these animals in battle was still a strange sight to the Greeks, and the Indian fighting line seemed to them like a city wall with towers. Porus did not think that his foes would venture to advance through the spaces left between the elephants. He argued that the horses would be terror-stricken and the foot would be met by the Indian foot soldiers if they tried to attack the elephants from the side, and that they would hesitate to move directly against them for fear of being trodden down by their onslaught.