"At each remove the lengthening chain" demands its group of guards, and these wisely disposed for quick mutual assistance; for with any enemy, and especially with one so mobile, it is impossible to be everywhere in sufficient force, superior to an unexpected attack. Communications are ever on the defensive, the most embarrassing of military attitudes. To the scattered units of such a system, all that can be provided is power to hold out until succoured. Moreover, there must be not merely a steady stream of supply from some far distant source, but the establishment of intermediate reservoirs--secondary depots--well stored with the manifold requirements of {p.308} an army in campaign; advanced bases, capable by themselves of supporting for an appreciable time the existence and activity of forces dependent upon them alone. The importance of these to the army make them ever an object of attack to the enemy. Provision against accident or interruption, casual or hostile, has therefore to be elaborate in framework and solid in joint. "Lord Roberts had 45,000 men when he arrived at Bloemfontein, and he increased that number to 75,000 by April 30." Six thousand horses, besides mules, were at the same time sent up. To supply men and animals with daily food, and to accumulate on the spot twenty-five days' provisions and supplies of military stores for the further advance to the Vaal, there had to be brought daily to Bloemfontein, besides the reinforcements of men, 1020 tons by a single-track railroad on which many bridges had been destroyed.[41] And Bloemfontein was 750 miles from Cape Town, and 250 from De Aar, the nearest secondary base so far established. [Footnote 41: These figures are taken from a speech made by the Under Secretary of War in Parliament, June 29, 1900.]