The German strategists had imagined that by withdrawing their troops over a long front they would throw out of gear all the preparations of the Allies for the spring offensive. What they actually did was to save their force in the Gommecourt peninsula from being cut off, which would surely have been their fate had they waited. But in the {22} larger issue they proved to be singularly ill-informed, for they had stayed their retreat at the very points of the line on which the offensive had been prepared, so that the plans of attack were neither modified nor delayed. That this is true is evident, since such tremendous blows as Arras in the north and Rheims in the south could not possibly have been delivered had the preparations only begun after the Hindenburg retreat. One of the most difficult problems of this attack was how to arrange it upon that section which was covered by the town of Arras. It is true that the German line was 1700 yards east of the market-place, but the suburbs extended right up to it, and it was fringed with houses. The town itself, in which the storming troops must assemble and through which all supports and supplies must pass, was full of narrow streets within easy range of the German guns, and previous French experience had proved that each exit was so carefully and accurately barraged by the German fire that it was most difficult for the troops to debouch from it. This problem was solved by a fine piece of military engineering. The large cellars and other subterranean excavations with which the place abounded were connected up and fresh tunnels constructed, so that it was eventually found to be possible to put three whole divisions underground, with permanent headquarters and every necessary detail, including water, electric light, and a three-foot tramway. This fine work was carried out by the New Zealand, the 179th, and the 184th Tunnelling Companies. A huge dressing-station with 700 beds was also constructed. In this great underground place of assembly the greater part of the Sixth {23} Corps was assembled, while many of the tunnels on the south side of the town were allotted to the use of the Seventh Corps. All this had been carried out during the winter in the anticipation of a big attack being made at this point. For purposes of communication, over 1000 miles of twin cable was buried in six-foot trenches or secured to the sides of tunnels. Besides these special preparations, the usual immense labour of preparing for a modern attack had been thoroughly carried out along the whole line, including the construction of very many gun positions, trench mortar emplacements, dressing-stations, and innumerable dumps of munitions and engineering stores. Some dislocation had been caused in the plans by a partial withdrawal in the enemies' front trenches upon March 18, opposite the right end of the British lines. The abandoned works were occupied