text:  The subterranean passages under the Rock provided the sole available office space , and in them was located the signal equipment by which we expected to keep in touch with the commanders of the three assault forces . The eternal darkness of the tunnels was here and there partially pierced by <unk> electric bulbs . <unk> , cold air in block @-@ long passages was heavy with stagnation and did not noticeably respond to the <unk> efforts of electric fans . Through the arched ceilings came a constant <unk> , <unk> , <unk> of surface water that faithfully but <unk> <unk> off the seconds of the <unk> , almost <unk> , wait which always occurs between completion of a military plan and the moment action begins . 
  