Frederik-Valdemar Olsen (24 May 1877 – 19 November 1962) was a Danish soldier who became a general and commander in chief of the Belgian Congo Force Publique.

He was born into a poor family, joined the Danish army, then in 1898 volunteered to serve in the Congo Free State.

He rose quickly through the ranks, and in 1909–1910 played an important role in a stand-off with German and British forces disputing the eastern border of what was now the Belgian Congo.

During World War I Olsen commanded a force that defended Northern Rhodesia against a German attack, then advanced from the south of Lake Kivu to take Tabora in what is now Tanzania.

[1] His father worked as a porter carrying passenger luggage between the Kalundborg railway station and the ferry to the island of Zealand, while his mother did odd jobs and ran a bakery.

He was assigned to the 1st Artillery Regiment, where he served in a battery commanded by Johan Stöckel, who had worked on construction of the Fort de Shinkakasa.

Stöckel's stories made him keen to serve in Africa, and he was engaged by Hans-Hugold von Schwerin for service in the Congo Free State.

[1] Olsen sailed from Antwerp to Boma in December 1898, and was assigned to the Irebu camp under commander Luc-Arthur-Joseph Jeuniaux.

On 7 December 1899 he joined the troops that were repressing the revolt that had begun in 1896 in the northeast of the Congo during the Congo-Nile expedition of Francis Dhanis.

[2] Lieutenant Paul Léon Delwart, head of the elite company of the Force Publique in Orientale Province, died on 19 August 1900.

[3] Olsen replaced Delwart as leader of the elite Belgian company in the Ruzizi-Kivu region, based in Uvira.

Due to a severe attack of malaria he temporarily handed over common of the column, but reached Uvira on 7 March 1903.

The Kivu frontier incident began when the British district commissioner John Methuen Coote notified the Belgians on 26 June 1909 that he was taking possession.

On 11 September 1914 he received a call for help from George Graham Percy Lyons, district commissioner of Abercorn in Northern Rhodesia, who was being attacked by the Germans.

Olsen took action since he considered the move would help protect Katanga, and his cycling battalions soon arrived in Rhodesia, where they remained until relieved by British reinforcements.

On 23 June 1915 General Charles Tombeur ordered that the remaining troops in Rhodesia prepare to leave for Kivu.

[2] Olsen was made lieutenant colonel of 23 January 1916 and was placed in command of the southern brigade for the Tabora Offensive.

[1] Olsen took leave in France, then returned to East Africa via the Suez Canal and Dar es Salaam.

In 1920 the Chamber and the Senate unanimously voted to make him a fully naturalized Belgian citizen (grande naturalisation belge).

[1] On 22 November 1920 Olsen was appointed colonel and became commander in chief of the Force Publique, which he reorganized for peacetime duties.

In 1953 a monument was erected in Bukavu for the force led by Olsen that had taken possession of the place for the Congo Free State.