Belgium established its independence in the revolution of 1830. Like the other European Great Powers, Britain was slow to recognise the new state. Even the election of Leopold of Saxe-Coburg, former son-in-law of Britain's King George IV and uncle to the future Queen Victoria, as King of the Belgians failed to win diplomatic recognition from London. Belgium's emergence had caused the break-up of the United Kingdom of the Netherlands, one of several buffer states established after the end of the Napoleonic Wars as a check against future French expansion, and London feared this newly formed nation would be unable to survive hostile expansion by its neighbours. A British-organised European Congress produced the Treaty of London of 1839, whereby the Great Powers (and The Netherlands) all formally recognised the independence of Belgium, and (at Britain's insistence) guaranteed its neutrality.