Alcibiades (28.2-28.3)

Thereupon he roused the spirits of the soldiers, declaring that they must now do sea-fighting and land-fighting and even siege-fighting, too, against their enemies, for poverty stared them in the face unless they were victorious in every way. He then manned his ships and made his way to Proconnesus, giving orders at once to seize all small trading craft and keep them under guard, that the enemy might get no warning of his approach from any source so ever.

Now it chanced that copious rain fell all of a sudden, and thunder-peals and darkness cooperated with him in concealing his design. Indeed, not only did he elude the enemy, but even the Athenians themselves had already given up all expectation of fighting, when he suddenly ordered them aboard ship and put out to sea. After a little the darkness cleared away, and the Peloponnesian ships were seen hovering off the harbor of Cyzicus.