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, St 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).
When were the Netherlands' colonies annexed by Napoleon?
1810