King of Belgians Leopold I manuscript letter in French, size 21 cm x 25.5 cm. 4 pages-2 of them blank+ envelope with red seal. Dated January 1845.

The letter announcement of the marriage of Princess Marie Caroline August of Salerno and Royal Highness Monsignor the Duke C’Aumale. 

Translation:

Mister my Brother and Cousin. It is with great satisfaction that I have received the letter for which your Majesty announces to me the marriage of the very dear Cousin (female sp.), Princess Marie Caroline August of Salerno with his Royal Highness Monsignor the Duke C'Aumale, for which was celebrated in Naples, last November 24th. Your Majesty has well-judged my sentiments by not doubting the part that I would take and the joy that he has caused in this happy event which, by establishing new ties of kinship between his August House and of mine will help to contribute more and more the friendships that already exist between our two hearts. I make ardent wishes for the happiness of the newlyweds, and I eagerly seize such a favorable occasion to renew to Your Majesty the assurances of the high esteem and the inalterable friendship with which will never cease to be.

Mister my Brother and Cousin 

Of Your Majesty, The good Brother and Cousin, 

Leopold

Brussels, the 12th of January 1845

Leopold I (1790 – 1865) was the first King of Belgians, reigning between July 1831 and December 1865.

The youngest son of Francis, Duke of Saxe-Coburg-Saalfeld, Leopold took a commission in the Imperial Russian Army and fought against Napoleon after French troops overran Saxe-Coburg during the Napoleonic Wars. After Napoleon's defeat, Leopold moved to the United Kingdom where he married Princess Charlotte of Wales, who was second in line to the British throne and the only legitimate child of the Prince Regent (the future King George IV). Charlotte died after only a year of marriage, but Leopold continued to enjoy considerable status in Britain.

After the Greek War of Independence (1821–32), Leopold was offered the throne of Greece but turned it down, believing it to be too precarious. Instead, he accepted the throne of Belgium in 1831 following the country’s independence in 1830. The Belgian government offered the position to Leopold because of his diplomatic connections with royal houses across Europe, and because as the British-backed candidate, he was not affiliated with other powers, such as France, which were believed to have territorial ambitions in Belgium which might threaten the European balance of power created by the 1815 Congress of Vienna.

Leopold took his oath as King of the Belgians on 21 July 1831, an event commemorated annually as Belgian Nations Day. His reign was marked by attempts by the Dutch to recapture Belgium and, later, by internal political division between liberals and Catholics. As a Protestant, Leopold was considered liberal and encouraged economic modernization, playing an important role in encouraging the creation of Belgium’s first railway in 1835 and subsequent industrialization. As a result of the ambiguities in the Belgium Constitution, Leopold was able to slightly expand the monarch's powers during his reign. He also played an important role in stopping the spread of the Revolutions of 1848 into Belgium. He died in 1865 and was succeeded by his son, Leopold II.