When tanks, the newly invented British weapon, were used for the first time in a mass attack on November 20 1917, they not only achieved one of the most remarkable successes of the First World War but set the pattern for the future of mechanized warfare. For the first time in three years of bloody trench warfare, epitomized by the slaughter at Passchendaele which was then reaching its climax, tanks brought about a breakthrough of the massive German...