Following the 1830 Belgian Revolution that split the country from the Kingdom of the Netherlands, the National Congress offered the crown to Leopold of Saxe-Coburg, a widower of Britain's Princess Charlotte. He accepted a constitutional monarchy with limited powers, and July 21 became Belgium's National Day, still celebrated with a military parade in Brussels.
Leopold was a careful political operator who had already turned down the throne of Greece before accepting Belgium's offer, calculating that the small, wealthy, strategically located kingdom suited him better. He insisted on a constitutional framework that curbed royal authority, a condition the fiercely independent Belgian Congress, wary of any new absolutism after throwing off Dutch rule, was happy to grant.
The new kingdom's birth was messy: the Dutch king William I refused to accept the split and launched the 'Ten Days' Campaign' just weeks after Leopold's coronation, an invasion only halted by French military intervention on Belgium's behalf. Belgium's independence wasn't fully recognized internationally until the 1839 Treaty of London, the same treaty whose guarantee of Belgian neutrality Germany would violate in 1914, triggering Britain's entry into World War I.
Leopold went on to become a shrewd matchmaker for European royalty, most famously helping arrange the marriage of his niece Victoria to his nephew Albert, making him, in a sense, grandfather to an entire generation of Europe's ruling houses.
Key people: Leopold I