On 9 April, birth in Brussels of Leopold, Louis, Philippe, Marie, Victor, son of Leopold I and Louise-Marie.
Prince Leopold entered the Senate, of which he was a member by right. On 22 August, he married Marie-Henriette of Habsburg-Lorraine, Arch-Duchess of Austria. They had four children: Louise-Marie (1858-1924), Leopold (1859-1869), Stephanie (1864-1945), Clementine (1872-1955).
On 17 December, Leopold took the constitutional oath.
On 12 December, the King Palace convened an international conference in Brussels of scientists, geographers and explorers, focusing on the discovery of the centre of Africa. This resulted in the setting up (1877) of an "association for the civilisation and exploration of Central Africa".
Leopold II set up, with the cooperation of the British explorer Stanley, the Study Committee on the Upper Congo, converted in 1879 into the International Association of the Congo.
The Berlin Conference recognised the independent state of the Congo, of which Leopold II became the Sovereign. That same year, the Belgian Parliament authorizes the King to be the Head of State of Congo.
In July, the Brussels International Conference condemned slavery and triggered the start of the anti-slavery campaign in Africa, at the instigation of the King.
On 19 September, Queen Marie-Henriette died in Spa.
Following the excesses committed by the Europeans in Africa, Leopold's reputation and his overseas venture were questioned. The King set up an International Commission of Inquiry, which recognised the merits of the royal action in Congo, while pointing out abuses and shortcomings.
The law of 18 October made the independent State of the Congo a Belgian colony.
On 14 December, the King signed the law on compulsory military service. He died three days later.