In the first part of this eagerly-awaited fourth volume, the authors in great detail study the fortifications built to face the Italian threat over the Alps. No stone is left unturned: development of the fortified south-eastern line, building the loftier fortifications, technical means and specific armament. The second part of Volume 4 exhaustively reviews the infantry and specific artillery which continuously from 1935 to 1940, held the south-eastern barrier. The importance of the subject has led the publishers and the authors to bring out Volume 5- coming shortly - for the saga to be complete without holding back on any information.