Quintus Curtius Rufus, History of Alexander 8.13.27

8.13.27

Vacua erat ab hostibus ripa, quae petebatur: quippe adhuc Porus Ptolomaeum tantum intuebatur. Una ergo navi, quam petrae fluctus inliserat, haerente ceterae evadunt, armaque capere milites et ire in ordines iussit.

All of a sudden the rain then ceased, but clouds so dense overspread the sky that they hid the light, and made it scarcely possible for men conversing together to see each other's faces. Any other leader but Alexander would have been appalled by the darkness drawn over the face of heaven just when he was starting on a voyage across an unknown river, with the enemy perhaps guarding the very bank to which his men were blindly and imprudently directing their course. But the king deriving glory from danger and regarding the darkness which terrified others as his opportunity, gave the signal that all should embark in silence, and ordered that the galley which carried himself should be the first to be run aground on the other side. The bank, however, towards which they steered was not occupied by the enemy, for Porus was in fact still intently watching Ptolemy only. Hence all the ships made the passage in safety except just one, which stuck on a rock whither it had been driven by the wind. Alexander then ordered the soldiers to take their arms and to fall into their ranks.