The size of Britain’s Atlantic empire or the empire of goods necessitated her large and strong navy to maintain trade and more importantly, to protect the transport of products and peoples, including African slaves. The slave trade had a central role in the transatlantic enterprise and made Britain a superior oceanic trading nation over its main maritime rivals, the French and the Dutch.
The debate opens with the relationship between Britain’s expanding transoceanic commercial network and the subsequent economic benefits for Britain. In the last quarter of the eighteenth
century, economists and politicians became increasingly argumentative over the issue. Writer and economist Adam Smith, who wrote Wealth of Nations in 1776, believed that the colonies only drained Britain of vital resources and thus did not benefit the nation. He pointed out instead that interest groups such as the merchants and planters gained all the profit, whilst the British government paid for administrative and defence costs of the empire. In contrast, Edmund Burke, who was a prominent speaker in the House of Commons in the 1780s, believed that the colonies were of “paramount economic importance” because the colonies accounted for a large share of British trade from one-twelfth in 1700 to one-third by 1775 of the total trade. There is no resolution, but instead only interpretation and speculation from
different experiences of British colonisation and the documentary evidence gathered since the period.
There are further debates that are concerned with the significance of British Atlantic commerce in relation to the process of industrialisation, or the impact of domestic demand in Britain on industrial output, and the role of foreign trade in metropolitan economic develop-ment. The most important and widely discussed factor is slavery. The slave trade played an intrinsically important part in the triangular trade system. First, Britain sold its manufactured goods to African traders on the West Coast, who in turn provided slaves, which were then traded in the American colonies for goods and capital sent to Britain. It is uncertain how many slaves were sold into slavery, but an approximate estimate of the number of African slaves carried in British ships between 1662 and 1807 is about 3.4 million. This figure accounts for half of all the slaves shipped from Africa to the Americas. Between 1660 and 1700, the annual shipment of slaves rarely exceeded 7,000, but within a century by the 1760s, this figure had increased six fold to over 42,000. The slave trade was predominantly British
based and therefore, undoubtedly had an impact on Britain’s commercial trade. For some, the slave trade was at the centre of Britain’s economy and Atlantic trade, whilst others have dismissed its significance altogether. The most influential and famous analysis of the relationship between slavery, American commerce and Britain’s economy was in Eric
Williams’ Capitalism and Slavery written in 1944. First of all, Williams, an economic historian, maintained that slavery and overseas commerce did contribute greatly to Britain’s industrialisation. This was because, as Williams argued, the slave trade and the sale of sugar
in Britain offered a substantial amount of the capital and the demand for the growth of British manufactured goods, and consequently, it was these two elements that proved to be the stimulus for Britain’s transition into an industrial nation. Also, in Williams’ analysis, he
noted that the entrepreneurs behind the colonial trade were the West India merchants and planters, who exerted their influence over economic and political matters in Britain.
However, contemporary historian David Richardson has argued that the contribution of the profits from slavery to capital investment in Britain has been overstated and never exceeded one per cent in the late 1780s. Still, there was a strong relationship and correlation between the expansion of the slave trade and the annual growth rate of industry, especially after the
Trade and opportunities for new markets intensified growth in the shipping sector in British ports. A larger and stronger navy was needed to accommodate a growing Atlantic empire of goods and slaves.  Subsequently, the cities of Liverpool and Bristol became major ports to service the triangular trade.  The profits from the slave trade were invested into the expansion of the city’s port and fleet. Liverpool became Britain’s leading slave trade port. Between 1750 and 1775, 1,868 ships left Liverpool for Africa.  By 1800, whilst Liverpool had invested in the slave trade, Bristol had committed its resources to the sugar trade; Manchester exported cotton in unequalled quantities; and Glasgow concentrated on tobacco.
However, Britain became gradually more dependant on colonial trade but this still implied that trade with Europe was an important source of revenue.

Britain by 1815 had destroyed rival navies. This was primarily a result of a series Navigation Acts that were introduced in the seventeenth and eighteenth centuries. The Navigation Acts dictated firstly that transoceanic commerce must be conducted in British ships sailed by British sailors, and secondly, there were restrictions on imports and exports from outside the British Atlantic empire. Thus the Navigation Acts effectively empowered the British navy to monopolise the trade of all its colonies.