unions between free white women and African-descended men, whether free, indentured or enslaved. Although born free to white women, the mixed-race children were considered illegitimate and were apprenticed for lengthy periods into adulthood. In an unusual case, Nell Butler was an Irish-born indentured servant of Lord Calvert. After she married an enslaved African, her indenture was converted to slavery for life under the 1664 Act. Further legislation would follow, entrenching and deepening the institution of slavery. Following the lead of Virginia, in 1671 the Assembly passed an Act stating expressly that baptism of a slave would not lead to freedom. Prior to this some slaves had sued for freedom based on having been baptized. The Act was apparently intended to save the souls of the enslaved; the legislature did not want to discourage slaveholders from baptizing his human property for fear of losing it. In practice, such laws permitted both Christianity and slavery to develop hand in hand. At this early stage in Maryland history, slaves were not especially numerous in the Province, being greatly outnumbered by indentured servants from England. The full effect of such harsh slave laws did not become evident until after large-scale importation of Africans began in earnest in the 1690s. During the second half of the 17th century, the British economy gradually improved and the supply of British indentured servants declined, as poor Britons had better economic opportunities at home. At the same time, Bacon's Rebellion of 1676 led planters to worry about the prospective dangers of creating a large class of restless, landless, and relatively poor white men (most of them former indentured servants). Wealthy Virginia and Maryland planters began to buy slaves in preference to indentured servants during the 1660s and 1670s, and poorer planters followed suit by c.1700. Enslaved Africans cost more than servants, so initially only the wealthy could invest in slavery. By the end of the seventeenth century, planters shifted away from indentured servants, and in favor of the importation and enslavement of African people. Eighteenth century During the eighteenth century the number of enslaved Africans imported into Maryland greatly increased, as the labor-intensive tobacco economy became dominant, and the colony developed into a slave society. In 1700 there were about 25,000 people in Maryland and by 1750 that had grown more than 5 times to 130,000. A great proportion of the population was enslaved. By 1755, about 40% of