In spite of the many gaps in our knowledge, the present picture of the Sahara in the aggregate is clear and coherent. The most radical transformation to date is that the Sahara has ceased to be an obstacle, a bulkhead interposed between Europe and Black Africa. The World War, which launched in North Africa the Turkish and Senusi drives, more than anything else, gave impetus to experimentation and the development of new methods of transportation and communication in the desert. The most immediate need was for telegraphic communications, which problem was quickly and easily solved by the wireless telegraph. Stations were installed throughout the English, Italian and French Sahara, and at once gave such excellent results that they became the essential cogs in the defense mechanism. The most up-to-date portion of the Sahara at present is that which extends between Algeria and the elbow of the Niger: the Tuareg Sahara of the great massifs around the Ahaggar.