Following slave revolts in the early 19th century, including Nat Turner's Rebellion in 1831, Virginia passed a law requiring black congregations to meet only in the presence of a white minister. Other states similarly restricted exclusively black churches or the assembly of blacks in large groups unsupervised by whites. Nevertheless, the black Baptist congregations in the cities grew rapidly and their members numbered several hundred each before the Civil War. (See next section.) While mostly led by free blacks, most of their members were slaves.