Tewodros II was the first emperor or negus of Abyssinia in almost 100 years to rule the entire empire, but it took the first five years of his reign, 1855-61, to eliminate rebels and re-conquer the provinces that had become virtually independent over the past decades of civil war. Abyssinia was more or less peaceful for a few short years between 1861 and 1863, but the military resources, money and energy it had required to re-establish the imperial borders had not allowed Tewodros to undertake other necessary activities. Essentially, he was a good general but a poor politician. In 1865, Menelik, the governor of Shewa province revolted again. Tewodros attempted to strengthen his position through an alliance with the British, but negotiations went badly wrong. In the summer of 1867, a British army landed to free some English hostages Tewodros had taken. The British stormed the negus' stronghold, and Tewodros committed suicide.

Abyssinia again fell into disorder. An Egyptian invasion in 1875 was defeated by Afar and Tigray warriors. Then the Italians invaded in 1885, backed up by British support. However, the governor of Tigray, Ras Alual, defeated the Italians at Dogali in 1887. That same year, Mahdists, a militant movement of Sudanese Muslims, attacked Abyssinia. The emperor Yohannis met the Mahdists in battle at Metema in 1889 and defeated them decisively, but he himself suffered a mortal wound. Upon his death, the governor of Shewa, Menelik, declared himself negus. Italy took the opportunity to establish itself in Eritrea and north Somaliland, while the British took south Somaliland, and the French occupied a small region around the port of Djibouti. Abyssinia was cut off from the sea. The Italians launched a new invasion from their coastal base in late 1895, but Menelik inflicted a humiliating defeat upon them at Adawa in 1896. This greatly increased Abyssinia's prestige, and the nation's independence was preserved. Menelik suffered a serious stroke in 1906, and his health declined until he died in 1913.

While Abyssinsia barely held onto its independence, a Muslim movement arose in the Sudan led by Muhammad Ahmad, who called himself the Mahdi, "servant of Mohammed", in 1881. The Mahdists, seeking to free the Sudan from Egyptian-British control, defeated a British army in 1883, (Egypt itself had been occupied by the British). The British governor of the Sudan, Gordon, was killed in 1885 defending the colonial capital, Khartoum. But revenge for his death would have to wait until 1898.

A mixed Egyptian-British army, about 20,000 men under General Kitchener met the main Mahdist army of up to 60,000 on September 2, 1898. The Sudanese horsemen, still relying on the charge with spear and sword, are slaughtered by long range rifle, artillery and machine gun fire. 11,000 Sudanese were killed and 16,000 wounded in exchange for a handful of British losses.