The Italians, helped by the British, who were trying to control Sudanese Muslim fanatics called Mahdists, secured a base on Ethiopia's Red Sea coastline at Massawa (Mitsiwa) in Eritrea in 1885; the Italians also purchased the port of Aseb in Eritrea from the local ruler. Desirous of exploiting more than the coastline area, they made a pact with the chieftain of Shewa (who later became Ethiopia's Emperor Menelik II [1844-1913] in 1889) and began, with British encouragement, to penetrate the Eritrean hinterland. Ethiopian forces of Emperor Yohannes (John) IV (18131-89) marched against the Italians, some 500 of who were surrounded and nearly all killed at the Battle of Dogali on January 26, 1887. Italy sent an army of 20,000 men in response, garrisoning it in Eritrea, but little fighting took place; eventually dysentery and fever caused its recall. Yohannes became preoccuped fighting the invading Mahdists in northern Ethiopia and died at the Battle of Metemma (Gallabat) on March 12, 1889. With the support of the Italians, Menelik now took the throne and soon negotiated the Treaty of Uccialli with Italy (May 2, 1889). The Italians interpreted the treaty as giving them a protectorate over Ethiopia, which Menelik rejected as unjustified according to the text (1891). But Britain accepted the Italian protectorate over Ethiopia.