Abdullah ibn Muhammad, Khalifa of Sudan

Abdullah ibn Muhammad or Abdullah Ibn-Mohammed or Abdullah al-Taashi or Abdullah al-Taaisha or Abdallahi ibn Muhammad or 'Abd Allah ibn Muhammad At-ta'i'shi, also known as "The Khalifa" (Arabic:  عبدالله بن سيد محمد خليفة)‎ (b. 1846, Sudan – d. November [24?] 25, 1899, Kordofan) was a Sudanese Ansar General and ruler who was one of the principal followers of Muhammad Ahmad. Ahmad claimed to be the Mahdi, building up a large following. After his death Abdallahi ibn Muhammad took over the movement, adopting the title of Khalifat al-Mahdi (usually rendered as "Khalifa"). His attempt to create an Islamist military dictatorship led to widespread discontent, and his eventual defeat and death at the hands of the British.

Abdullah followed his family’s vocation for religion. In about 1880 he became a disciple of Muḥammad Aḥmad, who announced that he had a divine mission, became known as al-Mahdī, and appointed Abdullah a caliph (khalīfah). When al-Mahdī died in 1885, Abdullah became leader of the Mahdist movement. His first concern was to establish his authority on a firm basis. Al-Mahdī had clearly designated him as successor, but the Ashraf, a portion of al-Mahdī’s supporters, tried to reverse this decision. By promptly securing control of the vital administrative positions in the movement and obtaining the support of the most religiously sincere group of al-Mahdī’s followers, Abdullah neutralized this opposition. Abdullah could not claim the same religious inspiration as had al-Mahdī, but, by announcing that he received divine instruction through al-Mahdī, he tried to assume as much of the aura as was possible.

Abdullah believed he could best control the disparate elements that supported him by maintaining the expansionist momentum begun by al-Mahdī. He launched attacks against the Ethiopians and began an invasion of Egypt.  But Abdullah had greatly overestimated the support his forces would receive from the Egyptian peasantry and underestimated the potency of the Anglo-Egyptian military forces, and in 1889 his troops suffered a crushing defeat in Egypt.

A feared Anglo-Egyptian advance up the Nile did not materialize. Instead Abdullah suffered famine and military defeats in the eastern Sudan. The most serious challenge to his authority came from a revolt of the Ashraf in November 1891, but he kept this from reaching extensive proportions and reduced his opponents to political impotence.

During the next four years, Abdullah ruled securely and was able to consolidate his authority. The famine and the expense of large-scale military campaigns came to an end. Abdullah modified his administrative policies, making them more acceptable to the people. Taxation became less burdensome. Abdullah created a new military corps, the mulazimiyah, of whose loyalty he felt confident.

However, in 1896 Anglo-Egyptian forces began their reconquest of the Sudan. Although Abdullah resisted for almost two years, he could not prevail against British machine guns. In September 1898 he was forced to flee his capital, Omdurman, but he remained at large with a considerable army. Many Egyptians and Sudanese resented the Condominium Agreement of January 1899, by which the Sudan became almost a British protectorate, and Abdullah hoped to rally support.  On November 24, 1899, a British force engaged the Mahdist remnants, and Abdullah died in the fighting.