What was the context in which Conrad's Heart of Darkness was written?

Heart of Darkness was published in 1899 as a serial and in 1902 as a book. During this time, the Congo Free State, where the novella takes place, was controlled by King Leopold II of Belgium as his personal domain. While he told the world he was a humanitarian, in reality, Leopold oversaw the extraction of ivory, rubber, and other valuable materials from the area under brutal conditions. While stating that he had outlawed slavery in the area, he employed a private police force to ensure that the local people met quotas for extracting rubber, and this force turned to flogging, rape, and murder to do so. They would also cut off the hands of children as part of their campaign of brutality. In 1903, Roger Casement, a worker in the British Foreign Office, published a report, called the Casement Report, that documented Leopold's abuses. As a result of this report, the Congo Reform Association was formed to publicize Leopold's actions, and, in 1908, the Congo was taken away from Leopold and became a Belgian colony known as the Belgian Congo.