Science and engineering skill came to the rescue, and with these under the guidance of a marvellous military genius that took in every situation, and turned it to his advantage, the enterprise was ultimately crowned with success. Hitherto military movements in the Soudan had been either by camels and weary foot trudging, or by boats on the Nile. Kitchener determined upon Wolseley's idea of crossing the desert between Wady Halfa and Abu-Hammed, but not by camels. He resolved to do it by rail, and to build the railway as they marched. It was a bold stroke. This is how it was done. Starting from {148} Wady Halfa, a surveying party set out for ten miles or so, making a rough survey of the lie of the ground, marking as they went the proposed course; about five miles behind the surveying parties came working parties 1200 strong, levelling and embanking where necessary. Two miles behind these came 550 platelayers, and half a mile after them a gang of 400 men to lift, straighten, and ballast the line. One mile behind these again came 400 men to put on the finishing touches, and the line was complete, but ever progressing to its ultimate terminus, carrying forward its own materials of rails and sleepers, as well as supplies for troops on the march. The credit of this great work was largely due to the young lieutenants of the Royal Engineers under the direction of Lieutenant Girouard, a Canadian officer. [Sidenote: On the Atbara] It was steady, plodding work; slow, perhaps, as a fighting campaign, but every mile of advance the army made sure of its position, and was kept within touch of Cairo. The campaign of 1897 found the greater part of the Sirdar's force as far as Ed-Damer, seven miles beyond the junction of the Nile and the Atbara river. Here a strong camp was formed and preparations were made for encountering the enemy who were massing some distance up the Nile at Matemneh, under Mahmoud, the son of the Khalifa, and old Osman Digna. These joined forces at Shendi, about half-way between Berber and Khartoum, their strength being about eighteen thousand men. General Kitchener, leading and directing every movement, returned from Cairo in December 1897, having arranged with the British Government for the sending out of a small British force to assist the Egyptian troops already in the field. {149} These were at once granted, and the reserve British force at Cairo, consisting of the 1st Warwicks, 1st Lincolns, and 1st Cameron Highlanders, left for the front, their places being taken by several regiments sent out from England.