midnight
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 .