Short rushes with small units occur quite naturally, because the platoon leader no longer succeeds in inducing his whole platoon to rise, since his influence extends only to the men nearest him, and because the flank squads at first remain behind and only gradually try to rejoin the leading skirmishers. If only a part of the skirmishers have jumped up, it is quite natural for them not to make a long rush, but to throw themselves down before reaching the new position, because of the feeling that they have been abandoned by their comrades and the fear of running into their field of fire. Thus, in spite of the best intentions of the leader, the short rush by small units occurs. In time of peace, however, we should retain the long rush by platoons and not endeavor to give human weaknesses the force of regulations. When once compelled to employ short rushes the following question presents itself: Is the advantage of such a small gain of ground worth the trouble of inducing the soldier to rise for making an advance by rushes? Would it, therefore, not be more profitable to =crawl forward=? A man crawling on his belly presents a vulnerable surface of approximately the size of a breast plate 50 cm. high. In an advance made by a large unit, or over covered terrain (fields of standing grain) crawling would be difficult (difficulty of maintaining the direction of march and reduction of the rate of advance); it would also be difficult to get men to advance to the charge after they have crawled along in this fashion for some time. The supervision of a unit crawling forward would also be exceedingly difficult. The following results were obtained in experiments made under favorable conditions: A distance of 500 m. was covered by crawling in about 10 minutes; crawling tired the men, increased the activity of the lungs to such an extent that deliberate aiming and firing was out of the question and the motion produced a noticeable swelling of arms, hands and knees.[89] The Boers occasionally used the following method: One man crept forward once or twice his own length, raising his body slightly, while the man next to him fired; then they exchanged roles and this procedure was repeated uninterruptedly. In any case, troops ought to be able to execute both the advance by rushes and the advance by crawling with or without firing. On terrain devoid of cover a skirmish line will frequently be able to advance only by crawling. [89] During the engagement at Paardeberg (18th February, 1900), the fighting line of the British 9th Infantry Division was reinforced by troops crawling up into the line, and carried forward to within 450 m. of the enemy’s position. An isolated assault was subsequently repulsed by the Boers.