So when the dry season brought the possibility of campaign, Humâyon had no choice but to retreat from the now daily increasing boldness of his enemy, and try to force his way back to Agra. In this he was stopped by the river Ganges, which it was necessary to cross in order to avoid an entrenched camp which he could neither pass nor hope to reduce. The bridge of boats took close on two months to complete, and then, a night or two before retreat became possible, the imperial camp was surprised about daybreak by the watchful enemy. It must have been a very complete surprise, for the emperor himself had only time to mount his horse, and after a vain appeal to his officers for one effort at least to repel the attack, accept their advice and ride for his life to the river-side. The bridge was not finished, there was no time for hesitation, so Humâyon urged his horse into the stream. It sank ere it could reach the shore, and the emperor would undoubtedly have done so likewise, but for the intervention of a water-carrier who was crossing with his skin bag, inflated with air, doing duty as a float. It proved enough to support two; Humâyon's life was saved, but his queen was left in Sher-Shâh's hands. The whole story has a smack of opium about it, and it seems more than probable that the young king, roused out of a drugged sleep, had not his wits about him. Nothing else can explain the fact of Babar's son running like a hare, and leaving his womenkind behind him. His wife appears, however, not to have suffered thereby in any way, not even in her affection for her handsome, thriftless king, for it was she, a childless widow, who after his death erected the splendid mausoleum at Delhi which bears his name. There is also something of opium in the promise which Humâyon made to the water-carrier, that _if_ he came to Agra, and _if_ he found Humâyon alive, he might, as a reward, claim to be king for a day. He did come, so we are told, and for a day sate on the throne of the Emperor of India. Humâyon, always fond of a joke, made merry over this one, and had prime fun in cutting up the water-carrier's skin bag into wads (which were duly stamped as coin in the mint), and in other merry antics, for he was light-hearted like his father. Nevertheless, the jest cost him dear, for it drew down on him the wrath of his sour brother Kamrân, who always nourished the secret belief--not an unfounded one--that he would have made a better king than his brother. This, however, was after Humâyon's generous condonation of both his brothers' grievous faults, and should have closed their lips from criticism. For both Kamrân and Hindal, seizing the opportunity of this disaster, claimed the throne, and marching on Agra from different sides, fell out over the question, until recalled to a sense of their common danger from the Bengal enemy.