The same principle of concentration prescribes that action when once begun should, at any rate at the decisive point, be sudden, rapid, and continuous. These fundamental ideas are illustrated by the practice of all the great commanders, and there is perhaps no better definition of a great commander than one whose action illustrates the simple principles of war. Lord Roberts is once more revealing to his countrymen the nature of these principles. The tangled mass of the war has suddenly become simplified, and there is clearness where there was confusion. The Commander-in-Chief reached Cape Town on January 10th, and found large forces dispersed over a front of two or three hundred miles, the reinforcements at sea, and the transport still in a state very like confusion. By February 6th, two or three weeks earlier than was anticipated by those at home who had the most perfect confidence in him, he was on his way to the front, enabling those at home to draw the certain inference that all was ready, the divisions assembled, and the transport in order. While he was travelling the six hundred miles from Cape Town to the Modder River various preliminary moves which he had ordered were in course of execution. There had been a large display of British infantry near Colesberg, covering the withdrawal of General French and the cavalry division. This had the effect of causing the Boers to reinforce Colesberg, probably by detachments from Magersfontein. The British infantry, however, was there only to lure the Boers; it was composed of parts of the sixth division on the way further north, and only a small infantry force was left to hold the reinforced Boers in check. The next move was a reconnaissance in force from Modder River to Koodoosberg Drifts, which drew Commandant Cronje's attention and some of his troops to his right flank. The reconnaissance had the further object of inspiriting the Highland Brigade which had been so badly damaged at Magersfontein, and of establishing good relations between these troops and their new commander, General Mac Donald. On their return to camp a short address from Lord Roberts had the effect upon them that Napoleon's proclamations used to produce on the French troops. A day or two was spent in completing the organisation of the force at Modder River, where a new division, the ninth, had been formed probably of troops brought up from the communications. The mounted infantry were also brigaded, as had been those at Orange River Station. Meantime various movements had been going on of which the details as yet are unreported. Two infantry divisions, the sixth and seventh, the last two from England, were moving towards the Riet River to the East of Jacobsdal. The point or points from which they started are not known, nor the direction of their march, which was screened by the cavalry division and perhaps also by a brigade of mounted infantry. At any rate on Sunday, the 11th inst., Hannay's brigade of mounted infantry from