The third principle of government which the Khalifa was compelled, or inclined, to adopt was to keep the relative power of the various tribes and classes conveniently proportioned. If an Emir rose to great influence and wealth, he became a possible rival, and suffered forthwith death, imprisonment, or spoliation. If a tribe threatened the supremacy of the Taaisha it was struck down while its menace was yet a menace. The regulation of classes and tribes was a far more complicated affair than the adjustment of individuals. Yet for thirteen years the Khalifa held the balance, and held it exact until the very end. Such was the statecraft of a savage from Kordofan. His greatest triumph was the Abyssinian war. It is not likely that two great barbaric kingdoms living side by side, but differing in race and religion, will long continue at peace; nor was it difficult to discover a cause of the quarrel between the Dervishes and the Abyssinians. For some time a harassing and desultory warfare disturbed the border. At length in 1885 a Dervish--half-trader, half brigand--sacked an Abyssinian church. Bas Adal, the Governor of the Amhara province, demanded that this sacrilegious robber should be surrendered to justice. The Arabs haughtily refused. The response was swift. Collecting an army which may have amounted to 30,000 men, the Abyssinians invaded the district of Gallabat and marched on the town. Against this host the Emir Wad Arbab could muster no more than 6,000 soldiers. But, encouraged by the victories of the previous four years, the Dervishes accepted battle, in spite of the disparity of numbers. Neither valour nor discipline could withstand such odds. The Moslems, broken by the fierce onset and surrounded by the overwhelming numbers of their enemies, were destroyed, together with their intrepid leader. Scarcely any escaped. The Abyssinians indulged in all the triumphs of savagery. The wounded were massacred: the slain were mutilated: the town of Gallabat was sacked and burnt. The Women were carried into captivity. All these tidings came to Omdurman. Under this heavy and unexpected blow the Khalifa acted with prudence. He opened negotiations with King John of Abyssinia, for the ransom of the captured wives and children, and at the same time he sent the Emir Yunes with a large force to Gallabat. The immediate necessities having thus been dealt with, Abdullah prepared for revenge.