King Leopold II then asked Gordon again to take charge of the Congo Free State. He accepted and returned to London to make preparations, but soon after his arrival the British requested that he proceed immediately to the Sudan, where the situation had deteriorated badly after his departure—another revolt had arisen, led by the self-proclaimed Mahdi, Mohammed Ahmed. The Mahdi is a messianic figure in Islam which tradition holds will appear at the dawn of every new (Islamic) century to strike down the enemies of Islam.