Belgian stamps Michel number 2 (issued in 1849), 3 and 4 (1851), depicting king Leopold I, the first king of Belgium, or more correct of the Belgians, according to the constitution of that country.

Leopold I, first King of the Belgians, was born as Leopold Georg Christian Friedrich in Ehrenburg Castle in the Bavarian town of Coburg, on December 16, 1790. He was the youngest son of Duke Francis Frederick of Saxe-Coburg-Saalfield.

In 1795 Leopold was appointed colonel of the Izmailovski Imperial Regiment in Russia. Seven years later he became a general. When Napoleonic troops occupied the Duchy of Saxe-Coburg in 1806 he went to Paris. Napoleon offered him the position of adjutant, but he refused. Instead he took up a military career in the Imperial Russian cavalry. Afterwards he campaigned against Napoleon. In 1815 Leopold reached the rank of field-marshal.

On May 2, 1816, he married Princess Charlotte Augusta, the only legitimate child of the British Prince Regent (later King George IV) and therefore heiress to the English throne. She died in 1817. Leopold functioned as a principal advisor to his niece, Queen Victoria, the daughter of his sister Viktoria of Saxe-Coburg-Saalfeld.

In 1830 Leopold was offered the Greek crown, but he refused it. After Belgium asserted its independence from the Netherlands on October 4, 1830, the Belgian National Congress asked Leopold to become king of the newly-formed country. He accepted and became "King of the Belgians" on June 26, 1831. He swore allegiance to the constitution in the Royal Palace in Brussels on July 21, 1831. This day became a Belgian national holiday. Less than two weeks later the Netherlands invaded Belgium. Skirmishes continued for eight years, but in 1839 the two countries signed a treaty establishing Belgium's independence.

In 1832, Leopold married Princess Louise-Marie Therese Charlotte Isabelle d'Orleans, daughter of King Louis-Philippe of France. Leopold and Louise had four children. One of Leopold's greatest achievements was building the first railway in continental Europe between Brussels and Mechelen on May 5, 1835.

On December 10, 1865, the king died in Laeken. He was succeeded by his son Leopold II.