text:  The land assault was frustrated when the channel between the two islands was found to be too deep to <unk> , and the American defenses prevented an amphibious landing . The naval bombardment had little effect due to the sandy soil and the <unk> nature of the fort 's <unk> log construction . <unk> fire by the defenders wrought significant damage on the British fleet , which withdrew after an entire day 's bombardment . The British withdrew their expedition force to New York , and did not return to South Carolina until <unk> . 
  