<P> The Napoleonic Wars were therefore ones in which Britain invested large amounts of capital and resources to win . French ports were blockaded by the Royal Navy, which won a decisive victory over a Franco - Spanish fleet at Trafalgar in 1805 . Overseas colonies were attacked and occupied, including those of the Netherlands, which was annexed by Napoleon in 1810 . France was finally defeated by a coalition of European armies in 1815 . Britain was again the beneficiary of peace treaties: France ceded the Ionian Islands, Malta (which it had occupied in 1797 and 1798 respectively), Mauritius, Saint Lucia, and Tobago; Spain ceded Trinidad; the Netherlands Guyana, and the Cape Colony . Britain returned Guadeloupe, Martinique, French Guiana, and Réunion to France, and Java and Suriname to the Netherlands, while gaining control of Ceylon (1795--1815). </P> <P> With the advent of the Industrial Revolution, goods produced by slavery became less important to the British economy . Added to this was the cost of suppressing regular slave rebellions . With support from the British abolitionist movement, Parliament enacted the Slave Trade Act in 1807, which abolished the slave trade in the empire . In 1808, Sierra Leone Colony and Protectorate was designated an official British colony for freed slaves . Parliamentary reform in 1832 saw the influence of the West India Committee decline . The Slavery Abolition Act, passed the following year, abolished slavery in the British Empire on 1 August 1834, finally bringing the Empire into line with the law in the UK (with the exception of St. Helena, Ceylon and the territories administered by the East India Company, though these exclusions were later repealed). Under the Act, slaves were granted full emancipation after a period of four to six years of "apprenticeship". The British government compensated slave - owners . </P> <P> Between 1815 and 1914, a period referred to as Britain's "imperial century" by some historians, around 10,000,000 square miles (26,000,000 km) of territory and roughly 400 million people were added to the British Empire . Victory over Napoleon left Britain without any serious international rival, other than Russia in Central Asia . Unchallenged at sea, Britain adopted the role of global policeman, a state of affairs later known as the Pax Britannica, and a foreign policy of "splendid isolation". Alongside the formal control it exerted over its own colonies, Britain's dominant position in world trade meant that it effectively controlled the economies of many countries, such as China, Argentina and Siam, which has been described by some historians as an "Informal Empire". </P> <P> British imperial strength was underpinned by the steamship and the telegraph, new technologies invented in the second half of the 19th century, allowing it to control and defend the empire . By 1902, the British Empire was linked together by a network of telegraph cables, called the All Red Line . </P>

Who controlled the world at the end of the 1800s