It seems probable that 25,000 Negroes a year arrived in America between 1698 and 1707. After the Asiento of 1713 this number rose to 30,000 annually, and before the Revolutionary War it had reached at least 40,000 and perhaps 100,000 slaves a year.
The total number of slaves imported is not known. Dunbar estimates that nearly 900,000 came to America in the sixteenth century, 2,750,000 in the seventeenth, 7,000,000 in the eighteenth, and over 4,000,000 in the nineteenth, perhaps 15,000,000 in all. Certainly it seems that at least 10,000,000 Negroes were expatriated. Probably every slave imported represented on the average five corpses in Africa or on the high seas. The American slave trade, therefore, meant the elimination of at least 60,000,000 Negroes from their fatherland. The Mohammedan slave trade meant the expatriation or forcible migration in Africa of nearly as many more. It would be conservative, then, to say that the slave trade cost Negro Africa 100,000,000 souls. And yet people ask to-day the cause of the stagnation of culture in that land since 1600!
Such a large number of slaves could be supplied only by organized slave raiding in every corner of Africa. The African continent gradually became revolutionized. Whole regions were depopulated, whole tribes disappeared; villages were built in caves and on hills or in forest fastnesses; the character of peoples like those of Benin developed their worst excesses of cruelty instead of the already flourishing arts of peace. The dark, irresistible grasp of fetish took firmer hold on men's minds.
Further advances toward civilization became impossible. Not only was there the immense demand for slaves which had its outlet on the west coast, but the slave caravans were streaming up through the desert to the Mediterranean coast and down the valley of the Nile to the centers of Mohammedanism. It was a rape of a continent to an extent never paralleled in ancient or modern times.
In the American trade there was not only the horrors of the slave raid, which lined the winding paths of the African jungles with bleached bones, but there was also the horrors of what was called the "middle passage," that is, the voyage across the Atlantic. As Sir William Dolben said, "The Negroes were chained to each other hand and foot, and stowed so close that they were not allowed above a foot and a half for each in breadth. Thus crammed together like herrings in a barrel, they contracted putrid and fatal disorders; so that they who came to inspect them in a morning had occasionally to pick dead slaves out of their rows, and to unchain their carcases from the bodies of their wretched fellow-sufferers to whom they had been fastened[75]."
It was estimated that out of every one hundred lot shipped from Africa only about fifty lived to be effective laborers across the sea, and among the whites more seamen died in that trade in one year than in the whole remaining trade of England in two. The full realization of the horrors of the slave trade was slow in reaching the ears and conscience of the modern world, just as to-day the treatment of dark natives in European colonies is brought to publicity with the greatest difficulty. The first move against the slave trade in England came in Parliament in 1776, but it was not until thirty-one years later, in 1807, that the trade was banned through the arduous labors of Clarkson, Wilberforce, Sharpe, and others.
Denmark had already abolished the trade, and the United States attempted to do so the following year. Portugal and Spain were induced to abolish the trade between 1815 and 1830. Notwithstanding these laws, the contraband trade went on until the beginning of the Civil War in America. The reasons for this were the enormous profit of the trade and the continued demand of the American slave barons, who had no sympathy with the efforts to stop their source of cheap labor supply.
However, philanthropy was not working alone to overthrow Negro slavery and the slave trade. It was seen, first in England and later in other countries, that slavery as an industrial system could not be made to work satisfactorily in modern times. Its cost was too great, and one of the causes of this cost was the slave insurrections from the very beginning, when the slaves rose on the plantation of Diego Columbus down to the Civil War in America. Actual and potential slave insurrection in the West Indies, in North and South America, kept the slave owners in apprehension and turmoil, or called for a police system difficult to maintain. In North America revolt finally took the form of organized running away to the North, and this, with the growing scarcity of suitable land and the moral revolt, led to the Civil War and the disappearance of the American slave trade.
There was still, however, the Mohammedan slave trade to deal with, and this has been the work of the nineteenth and early twentieth centuries. In the last quarter of the nineteenth century ten thousand slaves annually were being distributed on the southern and eastern coast of the Mediterranean and at the great slave market in Bornu.
On the east coast of Africa in 1862 nineteen thousand slaves were passed into Zanzibar and thence into Arabia and Persia. As late as 1880, three thousand annually were being thus transplanted, but now the trade is about stopped. To-day the only centers of actual slave trading may be said to be the cocoa plantations of the Portuguese Islands on the west coast of Africa, and the Congo Free State.