1810: Great Britain and Portugal signed an Anglo-Portuguese treaty that included a landmark anti-slave-trade clause, the first of many such international agr…

1810: Great Britain and Portugal signed an Anglo-Portuguese treaty that included a landmark anti-slave-trade clause, the first of many such international agreements. Under the terms of the treaty, the Portuguese agreed to give up the slave trade north of the equator, except for traffic between their own African possessions. The British government initially misinterpreted this clause as granting them a broad right to search and detain any Portuguese vessel found in those waters. This agreement signaled the beginning of a sustained British diplomatic campaign to secure international cooperation for the suppression of the traffic.