It was not probable that even the crews of the vessels would be aware of their close proximity till the word to board was given.

Unless some accidental and unguarded sound betrayed their advance, they might in all likelihood carry all before them by a surprise movement.
Julian was in the same boat as the officer in command of the expedition.

His intimate knowledge of the position of the war vessels would be of use in this murk and darkness.

Humphrey took an oar in the same boat; and the little fleet got together, and commenced its silent voyage just as the clocks of the fortress boomed out the midnight hour.
It was a strange, ghostly voyage.

There was a moon in the sky overhead, and the outlines of the hills and batteries, and even of the fortress itself, could be distinguished wherever the ground rose high enough; but wreaths of white vapour lay lazily along the water, or seemed to curl slowly upwards like smoke from some fire, and the boats rowed along in the encircling mist, only able to gain glimpses from time to time of the moonlit world as a puff of wind drove the vapour away from their path and gave them a transitory outlook upon their surroundings.
The dull roar of the guns filled the air.