This I find fascinating:

Although there were more Irish slaves in the Caribbean Isles than Africans, those peoples captured in wars with the English, knew nothing about tropical agriculture and were seen as “savages,” (they had a “dangerous nature”) (see Smedley 2007). They often ran away to join their co-religionists, the catholic Spanish, and were considered a “rebellious lot.” Historian Leonard Liggio, quoted from one letter sent to traders by a planter, “Don’t send us any more Irish; send us some Africans, for the Africans are civilized and the Irish are not” (1976, 8).

In contrast to Indians, Africans also had natural immunities to Old World diseases.European colonists recognized that Africans lived longer and were able to produce more than Europeans who had a high mortality rate. Moreover, Africans were in a strange land with no powerful allies and, unlike the Indians, could not escape to familiar territories. They were the most vulnerable of all the peoples of the Americas.

Sources of English servants began to decline in the latter part of the 17th century, as jobs became available at home. The slave trade to Africa increased as internal warfare in Africa made more and more people available for enslavement. Leaders of the colonies, all large planters, had two objectives: to impose effective social controls over the population and provide themselves withcheap and easily controlled workers. They readily perceived that they could use the differing physical characteristics of the population to divide them and demarcate some for permanent slavery. Historian Anthony Parent (2003) argues that a powerful planter class, acting to further its own economic interests, deliberately brought a new form of servitude, racial slavery to Virginia over the period of 1690-1723. In this period, hundreds of laws were passed restricting the rights of Africans and their descendents. By 1723, even free Negroes were prohibited from voting.

Colonial leaders were also doing something else; they were laying the basis for the invention of race and racial identities. They began to homogenize all Europeans, regardless of ethnicity, status, or social class, into a new category.

The first time the term “White,” rather than “Christian” or their ethnic names (English, Irish, Scots, Portuguese, German, Spanish, Swede) appeared in the public record was seen in a law passed in 1691 that prohibited the marriage of Europeans with Negroes, Indians, and mulattoes (Smedley 2007, 118). A clearly separated category of Negroes as slaves allowed newly freed European servants opportunities to realize their ambitions and to identify common interests with the wealthy and powerful. Laws were passed offering material advantages and social privileges to poor whites. In this way, colony leaders consciously contrived a social control mechanism to prevent the unification of the working poor (Allen 1997). Physical features became markers of racial (social) status, as Virginia’s governor William Gooch asserted, the assembly sought to “fix a perpetual Brand upon Free Negroes and Mulattos” (Allen 1997, 242).