The landing of the twenty slaves from the Dutch brig was the signal for all sorts of adventurers to embark in the same nefarious traffic. Worn-out and unseaworthy European ships, brigs, barks, schooners, and indeed, everything else that could float, no matter how unsafe, were brought into requisition to supply the demand for means of transportation in the new commerce. Thousands of persons incarcerated in the prisons of the old world were liberated upon condition that they would man these slave-trading vessels. The discharged convicts were used in the slave factories on the African coast, and even the marauding expeditions sent out from the slave ships in search of victims were mainly made up of this vile off-cast and scum of the prison population of England, France, Germany, Spain, and Portugal. So great was the increase of this traffic, that in a short time the importation in a single year amounted to forty thousand slaves. The immense growth of the slave population in the Southern States, soon caused politicians to take sides for or against the institution. This, however, did not manifest itself to any very great extent, until the struggle for National Independence was over, and the people, North and South, began to look at their interests connected with each section of the country. At the time that the Declaration of Independence was put forth, no authentic enumeration had been made; but when the first census was taken in 1791, the total number of slaves in what are now known as the Northern States, was forty thousand three hundred and seventy; in the Southern, six hundred and fifty-three thousand nine hundred and ten. It is very common at this day to speak of our revolutionary struggle as commenced and hurried forward by a union of free and slave colonies; but such is not the fact. However slender and dubious its legal basis, slavery existed in each and all of the colonies that united to declare and maintain their Independence. Slaves were proportionately more numerous in certain portions of the South; but they were held with impunity throughout the North, advertised like dogs or horses, and sold at auction, or otherwise, as chattels. Vermont, then a territory in dispute between New Hampshire and New York, and with very few civilized inhabitants, mainly on its southern and eastern borders, is probably the only portion of the revolutionary confederation never polluted by the tread of a slave. The spirit of liberty, aroused or intensified by the protracted struggle of the colonists against usurped and abused power in the mother-country, soon found itself engaged in natural antagonism against the current form of domestic despotism.