Slavery, serfdom and labor March 3, 1820 and March 6, 1820 – Slavery in the United States: The Missouri Compromise becomes law. 1820: Robert Owen devises the labour voucher. 1820: 18,957 black slaves leave Luanda, Angola. 1828 – 32,000 Angolans are sold in Rio de Janeiro, Brazil. June 5, 1829 – Slave trade: captures the armed slave ship Voladora off the coast of Cuba.
Slavery, serfdom and labor March 3, 1820 and March 6, 1820 – Slavery in the United States: The Missouri Compromise becomes law. 1820: Robert Owen devises the labour voucher. 1820: 18,957 black slaves leave Luanda, Angola. 1828 – 32,000 Angolans are sold in Rio de Jan.eiro, Brazil. June 5, 1829 – Slave trade: captures the armed slave ship Voladora off the coast of Cuba