About the Day
Leopold I was the first king of Belgium.
After Belgium gained its independence from the Netherlands on 4 October 1830, the Belgian National Congress, after considering several other candidates, asked Leopold to become king of the newly formed country. He accepted and became "King of the Belgians" on 26nd June 1831. He swore allegiance to the constitution in the Royal Palace in Brussels on 21st July 1831. This day became the Belgian national holiday.
Press Statement by Hillary Clinton,Secretary of State, USA
History of Kings of Belgium
Belgium National and Royal Anthem