While our left embraced the Argonne Forest, whose ravines, hills and elaborate, defense, screened by dense thick ets, had been generally considered impregnable. Reporting after the armistice to the Secretary of War, in these words General Pershing characterized a veritable jungle — the strongest of all German defenses on the whole front, from the North Sea to Switzerland. The fighting men who could pierce that vast fortress of nature, made doubly impenetrable by the diabolic ingenuity of the Boche, were to immortalize themselves in American history.