When the British under Herbert Kitchener moved into the Sudan in 1898, the Khalifa sent a force under Emir Mahmud Ahmad to join with Osman's army. Osman's plan to outflank Kitchener by moving up to Atbara was approved by the Khalifa, but Mahmud overruled Osman, when he proposed to move their forces even further upriver to Adaramra, threatening Kitchener's line of communications. Instead Mahmoud created a fortified defensive camp at Atbara.
The British invasion of the Sudan in 1898 led to a strategic clash between the Khalifa's forces and Osman's army. The conflict involved complex military maneuvers and decisions made by key figures like the Khalifa, Osman, and Mahmud.  Mahmud's decision to fortify at Atbara was a significant tactical move that aimed to protect his position against Kitchener's advance.