Repression of the Slave Trade in Africa

The British also aggressively pursued treaties with African powers, beginning on the east coast with the sultan of Zanzibar in 1838. The provisions included not only the ending of the slave trade but also most-favored-nation status for British commerce, freedom of religion, and freedom to trade with any individual or group.

Not surprisingly, there were few takers despite promises of subventions. When rulers in the Galinhas (Guinea-Bissau) signed such a treaty in 1840 under the guns of a British fleet, it was subsequently repudiated, as were treaties in Cabinda and Ambriz (Angola) signed under similar circumstances. The British lowered their demands, and the first ratified treaty was in the Cameroons the following year.

By 1857 there were forty-five such treaties, but it was not until the 1860s that they covered all the major embarkation points of the Atlantic slave trade. Even the king of Dahomey entered such an agreement, although given the impotence of British land-based forces at the time, he was able to break it with little fear of retribution. Whydah and Abomey, the Dahomey capital, were both beyond the reach of the British navy.

In fact, on the African side of the Atlantic, British measures against the slave trade may be viewed as the precursor to European partition of the subcontinent later in the century. The enormous buildup of the British navy off the African coast triggered a competitive response from the French who, despite having no treaties in place that would allow them to search any vessel flying a non-French flag, matched the British, cruiser for cruiser, in the mid-1840s. These vessels had no impact whatsoever on suppression of the slave trade.

The French also increased their territorial presence in Senegal and other places on the West African coast as a counterweight to rising British influence. For their part, the British effectively founded their largest colony in Africa, Nigeria, in 1851 when they occupied Lagos and drove out the slave traders at the second attempt.

From the standpoint of international law, these assaults were not different from the attacks on Brazil in the previous year. In the illegal phase of the traffic, many centers of the slave trade shifted from offshore islands to secluded estuaries and inlets that were clearly within the jurisdiction of African states.

British naval officers did not always obtain African permission before launching these attacks. More fundamentally, the large European presence and the willingness of European navies to intervene in business disputes between African and European merchants tilted the commercial balance toward the European side for the first time in four centuries of commercial exchange in West Africa. Increasingly, where African polities had formerly provided the rule of law and the security that commercial exchange required, now it was provided by various European powers.