The Treaty of London of 1839 signed on April 19, 1839. Its main historical significance was Article 7, which committed the United Kingdom to guard Belgium's neutrality in the event of invasion.

Belgium had previously been a part of the Netherlands. With the treaty, the Netherlands gave up its southern provinces to Belgium, and the province of Limburg was split in a Belgian and Dutch part. Belgium's de facto independence had been established through various major events in Europe (not the least of which was the Napoleonic Wars). The signatories of the treaty (the United Kingdom, Austria, France, Prussia, Russia, and the Netherlands) now officially recognized the independent country of Belgium, and gave Britain this special role.

The treaty was an important document, especially in its role in expanding World War I. The German government asked the British government, in 1914, to ignore the "scrap of paper" compelling Britain to guard Belgium's neutrality. Britain refused, and eventually, Germany invaded Belgium. At that point, British Prime Minister Herbert Asquith declared war on August 4 of the same year.

The 1839 Treaty of London is also referred to as the Convention of 1839.

See also

• Treaty of London - list of other treaties of London.