74 A HISTORY OF AMERICA IN 100 MAPS
In 1713 the Spanish granted the British the exclusive
right to supply their New World colonies with slaves.
This grant of the “Asiento” in South America also
coincided with an increased demand for slavery in the
British colonies. In fact, the growth of labor-intensive
crops—Caribbean sugar, Virginia tobacco, and
Carolina rice—directly stimulated the slave trade.
By 1750 the British were importing 50,000 to 60,000
Africans each year to their colonies, nearly half of
whom came through South Carolina’s booming port
of Charleston.
Among the strongest advocates of the British
slave trade was the political economist Malachy
Posthlethwayt, who sought to make West Africa a
center of the British empire in the 1730s and 1740s.
But this future, he warned, was threatened by the
current state of trade along the West African coast.
Postlethwayt saw British merchants undercutting one
another, which in turn made it easier for the French,
Portuguese, and Dutch to enlarge their own share of
the trade. In his mind, the best way to strengthen the
British position in West Africa was to consolidate all
commercial exchange within the newly established
Royal African Company. This would also advance a
mercantilist system whereby African slaves would
be paid for by British products and East Indian
commodities.
Postlethwayt drew a map to promote this
mercantilist vision and Britain’s position in the slave
trade more generally. The lengthy annotations at
ENGLAND AND THE SLAVE TRADE
Malachy Postlethwayt, “A New and
Correct Map of the Coast of Africa,”
1757
left detail the imperial rivalries at work along the
crowded Cape Coast. To highlight the even more
frenzied activity on the Gold Coast, he drew an inset
map that used national flags to identify the rival
imperial interests at each port or point of entry. He
first published his map in 1746 in a full-throated
defense of the Atlantic slave trade in which he called
for the British to fortify and protect their ports along
the coast.
Postlethwayt’s map reminds us how crucial slavery
was to the survival and prosperity of the colonies. The
Atlantic slave trade, he wrote, affords “our Planters a
constant Supply of Negroe-Servants for the Culture of
their Lands in the Produce of Sugars, Tobacco, Rice,
Rum.” That “Negroe-Trade” provided the British with
an “inexhaustible Fund of Wealth and Naval Power.”
For this reason, Postlethwayt urged that British
positions on the Slave Coast be reinforced, for these
were the key to extending the empire into the interior.
Along the coast of the map, he reminds readers that
the British had opportunities to expand commerce
into the interior, though they had been rebuffed by
the French along the far western coast, north of the
River Gambia.
Even as early as 1750, the slave trade had
prompted criticism, which Postlethwayt countered
by arguing that slaves were far better off in service
to British planters than subject to ongoing warfare
at home in Africa. But by 1757 Postlethwayt himself
had become an ardent critic of the slave trade. He
remained, however, a firm advocate of the expansion
of imperial interests in West Africa, and insisted that
the way for the British to end the trade was through
expanded commerce with interior African kingdoms.
All told, from 1607 to 1807 over 3 million Africans
were sent to the Americas through the British
slave trade.