“Nothing symbolizes the mayhem of the 1914-18 war more than those crude lines of defense, so it is fitting that one of the most dramatic features of London’s newly redesigned [IWM] is a re-creation of a trench. More than 52 feet of dark, claustrophobic passageway, 8 feet high, filled with the infernal racket of whizzing shells, the rat-a-tat of machine guns, the roar of planes.”