Mahmud received permission to advance at the end of January. He eagerly obeyed the longed-for order. But the whole situation was now changed. The Egyptian army was concentrated; the British brigade had arrived; the railway had reached Geneinetti; the miserable hamlet of Dakhila, at the confluence, had grown from a small depot to a fort, and from a fort to an entrenched camp, against which neither Dervish science nor strength could by any possibility prevail. Perhaps Mahmud did not realise the amazing power of movement that the railway had given his foes; perhaps he still believed, with the Khalifa, that Berber was held only by 2,000 Egyptians; or else--and this is the most probable--he was reckless of danger and strong in his own conceit. At any rate, during the second week in February he began to transport himself across the Nile, with the plain design of an advance north. With all the procrastination of an Arab he crawled leisurely forward towards the confluence of the rivers. At El Aliab some idea of the strength of the Atbara entrenchment seems to have dawned upon him. He paused undecided. A council was held. Mahmud was for a continued advance and for making a direct attack on the enemy's position. Osman Digna urged a more prudent course. Many years of hard fighting against disciplined troops had taught the wily Hadendoa slaver the power of modern rifles, and much sound tactics besides. He pressed his case with jealous enthusiasm upon the commander he detested and despised. An insurmountable obstacle confronted them. Yet what could not be overcome might be avoided. The hardy Dervishes could endure privations which would destroy the soldiers of civilisation. Barren and inhospitable as was the desert, they might move round the army at the Atbara fort and so capture Berber after all. Once they were behind the Egyptians, these accursed ones were lost. The railway--that mysterious source of strength--could be cut. The host that drew its life along it must fight at a fearful disadvantage or perish miserably. Besides, he reminded Mahmud--not without reason--that they could count on help in Berber itself.