The colonial history of Angola is usually considered to run from the appearance of the Portuguese under Diogo Cão in 1482 (Congo) or 1484 (Angolan coast)until the independence of Angola in 1975. Settlement did not begin until Novais's establishment of São Paulo de Loanda (Luanda) in 1575, however, and the Portuguese government only formally incorporated Angola as a colony in 1655<span>[citation needed]</span> or on May 12, 1886.<span />
Considering that slavery originated sometime in the 1620s in North America, and that it lasted until 1865, the correct answer to how much it lasted should be around 245 years.
It established the principle that everyone is subject to the law. Even the king. It also guaranteed the rights of individuals, and the right to a fair trial.