Aratus (21.1-21.2)

When all things were ready, Aratus ordered the rest of his forces to pass the night under arms, and taking with him four hundred picked men, few of whom knew what was on foot themselves, led them towards the gate of Corinth near by the temple of Hera. It was midsummer, the moon was at its full, and the night was cloudless and clear, so that they feared lest the gleam of their arms in the moonlight should disclose them to the sentinels.

But just as the foremost of them were near the wall, clouds ran up from the sea and enveloped the city itself and the region outside, which thus became dark. Then the rest of them sat down and took off their shoes, since men make little noise and do not slip if they are barefooted when they climb ladders; but Erginus, taking with him seven young men equipped as travellers, got unnoticed to the gate.