When slave prices rose to high levels after the war of 1812 systematic smuggling began to prevail from Amelia Island on the Florida border, and on a smaller scale on the bayous of the Barataria district below New Orleans; but these operations were checked upon the passage of a congressional act in 1818 increasing the rewards to informers. Another act in the following year directed the President to employ armed vessels for police in both African and American waters, and incidentally made provisions contemplating the return of captured slaves to Africa. Finally Congress by an act of 1820 declared the maritime slave trade to be piracy.[33] Smuggling thereafter diminished though it never completely ceased.
[Footnote 33: DuBois, _Suppression of the Slave Trade_, pp. 118-123.]
As to the dimensions of the illicit importations between 1808 and 1860, conjectures have placed the gross as high as two hundred and seventy thousand.[34] Most of the documents in the premises, however, bear palpable marks of unreliability. It may suffice to say that these importations were never great enough to affect the labor supply in appreciable degree. So far as the general economic régime was concerned, the foreign slave trade was effectually closed in 1808.
[Footnote 34: W.H. Collins, _The Domestic Slave Trade of the Southern States_ (New York [1904], pp. 12-20). _See also_ W.E.B. DuBois, "Enforcement of the Slave Trade Laws," in the American Historical Association _Report_ for 1891, p. 173.]
At that time, however, there were already in the United States about one million slaves to serve as a stock from which other millions were to be born to replenish the plantations in the east and to aid in the peopling of the west. These were ample to maintain a chronic racial problem, and had no man invented a cotton gin their natural increase might well have glutted the market for plantation labor. Had the African source been kept freely open, the bringing of great numbers to meet the demand in prosperous times would quite possibly have so burdened the country with surplus slaves in subsequent periods of severe depression that slave prices would have fallen virtually to zero, and the slaveholding community would have been driven to emancipate them wholesale as a means of relieving the masters from the burden of the slaves' support. The foes of slavery had long reckoned that the abolition of the foreign trade would be a fatal blow to slavery itself. The event exposed their fallacy. Thomas Clarkson expressed the disappointment of the English abolitionists in a letter of 1830: "We certainly have been deceived in our first expectations relative to the fruit of our exertions. We supposed that when by the abolition of the slave trade the planters could get no more slaves, they would not only treat better those whom they then had in their power, but that they would gradually find it to their advantage to emancipate them. A part of our expectations have been realized; ... but, alas! where the heart has been desperately wicked, we have found no change. We did not sufficiently take into account the effect of unlimited power on the human mind. No man likes to part with power, and the more unbounded it is, the less he likes to part with it. Neither did we sufficiently take into account the ignominy attached to a black skin as the badge of slavery, and how difficult it would be to make men look with a favourable eye upon what they had looked [upon] formerly as a disgrace. Neither did we take sufficiently into account the belief which every planter has, that such an unnatural state as that of slavery can be kept up only by a system of rigour, and how difficult therefore it would be to procure a relaxation from the ordinary discipline of a slave estate."[35]
