nine o'clock
Alone , she gave way to grief , to be comforted by her faith in One Unseen . Many soldiers had deserted , so every night , at sundown , sentinels patroled the wharves , and boats manned by sailors and marines kept vigilant watch in Charles River and far down the harbor . Robert must go to the shipyard before sundown and remain secreted till well into the night . The new moon would go down at nine o'clock ; the tide then would be half flood . What route should he take ? Were he to go directly up the Charles River to join the army at Cambridge , he must run the gauntlet , not only of three or four of the warships , but of the marine patrol in the river and the sentinels on both banks . If he were to strike eastward toward the Mystic , he would encounter the guard in that direction and the warship Scarborough anchored in the channel .