The number of vessels now engaged in carrying on a lawful trade in these rivers is between fifty and sixty; and so decided are the advantages reaped by the natives from this change in their commercial affairs, that it is not believed they would ever revert to it again, even if all outward restraints were taken away. So long as the African seas were given up to piracy and the slave-trade, and the aborigines in consequence were kept in constant excitement and warfare, it was almost impossible either to have commenced or continued a missionary station on the coast for the improvement of the natives. And the fact that there was none anywhere between Sierra Leone and the Cape of Good Hope, previous to the year 1832, shows that it was regarded as impracticable.[34] Christianity does not invoke the aid of the sword; but when she can shield from the violence of lawless men by the intervention of “the powers that be,” or when the providence of God goes before and smoothes down the waves of discord and strife, she accepts it as a grateful boon, and discharges her duty with greater alacrity and cheerfulness. Throughout all the region where the slave-trade was once carried on, there is great decline in business, except where that traffic has been replaced by legitimate commerce or agriculture. Nor could it well be otherwise. The very measures which were employed in carrying on this detestable traffic at least over three-fourths of the country, were in themselves quite sufficient to undermine any government in the world. For a long term of years the slaves were procured on the part of these larger and more powerful governments by waging war against their feebler neighbors for this express purpose; and in this way they not only cut off all the sources of their own prosperity and wealth, but the people themselves, while waging this ruthless and inhuman warfare, were imbibing notions and principles which would make it impossible for them to cohere long as organized nations. The bill for the abolition of the British slave-trade received the royal assent on March 25, 1807; and this law came into operation on and after January 1, 1808. That was a deed well done; and glorious was the result for humanity. To William Wilberforce, Thomas Clarkson, Granville Sharp, and a few others, is the credit due for this great act. Although the slave-trade was abolished by the British government, and afterwards by the American and some other nations, the slave-trade still continued, and exists even at the present day, in a more limited form, except, perhaps, in Northern and Central Africa, and on the Nile. In that section the trade is carried on in the most gigantic manner. It begins every year in the month of August, when the traders prepare for a large haul.