if they could fend off the fire-ships , the harwood might be saved from immediate destruction ; grey 's fear was that whatever was going on in the rear of the encampment was a ruse designed to pull men away from the shore , leaving the ship protected only by her marines , should the french then send down a barge loaded with explosives , or a boarding craft , hoping to elude detection whilst everyone was dazzled or occupied by the blazing fire-ships and the raid .