The right bank, on which lay the Macedonians, was high and hilly. The left bank was a wide, fertile plain. Alexander could hide his movements, while observing those of Porus. When he saw that the Indian king had ceased to march out to meet his feigned crossings, he began to prepare for a real one, meanwhile keeping up the blind. Seventeen miles above the camp was a wooded headland formed by a bend in the river and a small affluent, capable of concealing a large force, and itself hidden by a wooded and uninhabited island in its front. This place Alexander connected by a chain of couriers with the camp, and laid posts all along the river, at which, every night, noisy demonstrations were made and numerous fires were lighted, as if large forces were present at each of them. When Porus had been quite mystified as to Alexander’s intentions, Craterus was left with a large part of the army at the main camp, and instructed to make open preparations to cross, but not really to do so unless Porus’ army and the elephants should move up-stream. Between Craterus and the headland, Alexander secreted another large body, with orders to put over when he should have engaged battle. He himself marched, well back of the river and out of sight,--there was no dust to betray him,--to the headland, where preparations had already been completed for crossing. The night was tempestuous. The thunder and rain, usual during the south-west monsoon, drowned the noise of the workmen and moving troops and concealed the camp-fires, as well as kept Porus’ outposts under shelter. Alexander had caused a number of boats to be cut in two for transportation, but in such manner that they could be quickly joined for use,--the first mention we have of anything like pontoons. Towards daylight the storm abated and the crossing began. Most of the infantry and the heavy cavalry were put over in the boats. The light cavalry swam across, each man sustaining himself on a hay-stuffed skin, so as not to burden the horses. The movement was not discovered until the Macedonians had passed the island, when Porus’ scouts saw what was doing and galloped off with the news. It soon appeared that the army had not landed on the mainland, but on a second island. This was usually accessible by easy fords, but the late rains had swollen the low water from it to the shore to deep and rapid torrent. Here was a dilemma. Unless the troops were at once got over, Porus would be down upon them. There was no time to bring the boats around the island. After some delay and a great many accidents, a place was found where, by wading to their breasts, the infantry could get across. This was done, and the cavalry, already over, was thrown out in front. Alexander, as speedily as possible, set out with his horse, some five thousand strong, and ordered the phalanx, which numbered about six thousand more, to follow on in column, the light foot to keep up, if possible, with the cavalry.