An "Illegal" Repression

But the fascinating fact is that many of the British actions were illegal. In conducting their campaign against the slave trade, the British frequently broke even the nascent dictates of early-nineteenth-century international law. During the Napoleonic Wars they assumed belligerent rights to stop and search the ships of all nations, and whenever they came across a slave trader, they further assumed that their own abolition law applied and thus confiscated vessel and captives alike. An extremely vague declaration against the slave trade in an 1810 treaty with Portugal was taken as a basis for capturing dozens of Portuguese slave ships, even though Portugal was a wartime ally. The British law officers themselves could make no sense of the clause, and heavy reparations were paid.

At the end of the war, the navy's belligerent rights came to an end, yet it continued to detain French and Spanish slave vessels quite illegally. When again the law officers disavowed such tactics, the government attempted to negotiate, first, a right of search and, second, an anti-slave-trade treaty with every other maritime nation. When the Brazilian and Portuguese governments refused to comply, or in one case to extend a treaty to which they had agreed, the British parliament passed legislation allowing the navy to try any slave vessels flying a Brazilian or Portuguese flag into English courts an unprecedented extension of British law to foreign nationals.

The British foreign secretary, Lord Palmerston, used secret service funds to bribe Brazilian politicians (including the negotiator of the anti-slave-trade treaty), subsidize Brazilian newspapers that would print anti-slave-trade material, and hire a network of spies around the Atlantic world. Finally, in 1850, Palmerston authorized the navy to invade Brazilian waters and destroy the property of slave traders, a clear casus belli.