The investing troops on the south bank were then withdrawn; but a corps remained on the north bank to cover the removal of the heavy artillery to Elvas. Of the duty performed by Major Dickson on this occasion, under Marshal Beresford’s orders, Napier writes that “the arrangements for carrying off the stores were admirably executed; ... and that the transactions were so well masked by the 4th Division, which, in concert with the Spaniards, continued to maintain the investment, that it was only by a sally on the rear-guard, in which the Portuguese piquets of the 4th Division were very roughly treated, that the French knew the siege was raised.” The same author visits the failure of this siege, and the heavy losses attending all the subsequent sieges carried on by the British in Spain, on the absence of any properly-equipped corps of Sappers and Miners to assist the officers of Engineers. The want of such a corps, with the necessary implements, rendered, according to Napier, the British sieges a mere succession of butcheries. But Sir Alexander Dickson was ready to accept part of the responsibility of this failure for his own department. In his diary of the first siege of [Sidenote: Sir A. Dickson’s MSS.] Badajoz he wrote: “Every praise was due to the Portuguese Artillery for the activity, zeal, and willingness they displayed in this service. Indeed, nothing could exceed their personal exertions; but, from their professional inexperience, Major Dickson has great doubts whether a satisfactory result would have been obtained without the assistance of a proportion [Sidenote: Dated Elvas, 22 May, 1811.] of better-trained Artillerymen.” At the same time, however, he distinctly stated, in a letter to General Macleod, that his wish was not to begin the fire from any one battery until the whole attack should be more advanced, and that the Cristoval attack should be supported from other points. He added that the battery against the Picurina, although well placed as an auxiliary for general attack, afforded no support to that against San Cristoval. In these points, he wrote, “my opinions coincide entirely with those of Colonel Fletcher (R.E.), with whom it is a pleasure to serve.”