So that the task set the hardy sailors was not without its distinct element of peril, which was perhaps its chiefest attraction.
The shades of night gathered slowly over land and sea.

It seemed to Humphrey and some of those waiting in the boats as though night had never fallen so slowly before.

But their eyes were gladdened by the sight of the soft fog wreaths which crept over the water as the dusk fell, lying upon it like a soft blanket, and blotting out the distance as much as the darkness could do.
It was not a heavy fog.

The sailors were in no danger of losing their way as they rowed, first for the harbour mouth, and then for the two French warships at anchor beneath the batteries.

But it was thick enough to hide their approach from those on land.