It was all in vain, however; it was too late when he arrived at the pass. Darius had gone through with all his army. Alexander stopped to rest his men, and to allow time for those behind to come up. He then went on for a couple of days, when he encamped, in order to send out foraging parties--that is to say, small detachments, dispatched to explore the surrounding country in search of grain and other food for the horses. Food for the horses of an army being too bulky to be transported far, has to be collected day by day from the neighborhood of the line of march.