But the lesson was learned, eventually, that the long-range rifle, with its incessant fire and the Boer precision of aim, required a complete change in offensive operations. After the disasters to Buller and Methuen the tactics developed into operations more creditable from a modern point of view. With the advent of Lord Roberts, flanking became the feature of the British advance. The Boer forces have never been of sufficient strength to withstand a flanking movement by the British; they have always been compelled to withdraw whenever the flanking columns reached a point that would menace their retreat. When the British came into Pretoria, the officers and correspondents all complained of what they called lack of pluck in the Boer as a fighter, as shown in the operations north of Bloemfontein; but in no instance at that part of the campaign did they have an opportunity to defend themselves against purely frontal attack, like those in which General Buller made himself conspicuous for his fatal old-fashioned tactics. Lord Roberts’s army was in sufficient strength, so that he could employ a main force of infantry and artillery of from 30,000 to 40,000, and could send out flanking columns, of cavalry and mounted infantry with a few horse batteries, of about 10,000 each. Thus, when a Boer position was developed, the main advance took an artillery position at long range and maintained an incessant shell fire, while the mounted troops were sent out on either flank in an attempt to cut off the retreat of the burghers. As soon as these flanking columns reached a certain point from which a junction of the two forces might be made, the Boers were compelled to withdraw, in many cases without firing a shot. Sometimes this column of cavalry or mounted infantry would be fifteen or twenty miles away on their flank; but owing to their admirable signal service and their perfect scouting they were able to keep informed as to the enemy’s whereabouts, and at the last moment, just before a junction was made to cut off their retreat, they would slip through. Cronje’s capture at Paardeburg was due to the fact that he misjudged the movements of the troops on his flank. His officers begged him to retire, but he insisted on holding the position one day longer. That delay of one day proved to be fatal; on the next morning he was surrounded by about 40,000 of the enemy, with overwhelming batteries. After twelve days of the most heroic defense, when his ammunition was expended, and the action of the heat on the dead bodies in his laager made it intolerable, he was compelled to surrender. That was the only time the British succeeded in capturing any large number by the flanking movement, although they always succeeded in preventing any serious opposition to their advance.