Question: Cap-Haïtien became the capital of the Kingdom of Northern Haiti under a king that was a former slave of what ethnicity?

Context paragraphs:
Citadelle Laferrière: The Citadelle Laferrière or, Citadelle Henry Christophe, or simply the Citadelle (English: Citadel ), is a large mountaintop fortress in Nord, Haiti, located on top of the mountain Bonnet a L’Eveque, approximately 17 mi south of the city of Cap-Haïtien, 10 mi southwest of the Three Bays Protected Area, and 5 mi uphill from the town of Milot.  It is one of the largest fortresses in the Americas and was designated by the United Nations Educational, Scientific and Cultural Organization (UNESCO) as a World Heritage Site in 1982—along with the nearby Sans-Souci Palace.  The mountaintop fortress has itself become an icon of Haiti.  The Citadel was built by Henri Christophe, a key leader during the Haitian slave rebellion (1791–1804), after Haiti gained independence from France at the beginning of the 19th century.

Henri Christophe: Henri Christophe (] ; 6 October 1767 – 8 October 1820; used the anglicized version of Henry Christopher) was a former slave of Bambara ethnicity, and perhaps of Ibo descent, and key leader in the Haitian Revolution, which succeeded in gaining independence from France in 1804.  In 1805 he took part under Jean-Jacques Dessalines in the capturing of Santo Domingo (now Dominican Republic), against French forces who acquired the colony from Spain in the Treaty of Basel.

Second Empire of Haiti: The Second Haitian Empire, officially known as the Empire of Haiti (French: Empire d'Haïti, Haitian Creole: Anpi an Ayiti), was a state which existed from 1849 to 1859.  It was established by the then-President, former slave Faustin Soulouque, who, inspired by Napoleon I, declared himself Emperor Faustin I of Haiti on August 26, 1849 at the Cathedral of Our Lady of the Assumption in Port-au-Prince.  Faustin's unsuccessful invasions in attempt to reconquer the Dominican Republic (in 1849, 1850, 1855 and 1856), which seceded from Haiti in 1844, undermined his control over the country.

Mahommah Gardo Baquaqua: Mahommah Gardo Baquaqua was a former slave, native of Zooggoo, West Africa, a tributary kingdom of Bergoo kingdom.  He worked in Brazil as a captive, however he escaped and fled to New York in 1847, assuring his freedom.  He wrote a biography, published by American abolitionist Samuel Moore in 1854.  His report is the only known document about slave trade written by a Brazilian former slave.

Henri Christophe: A Chronicle in Seven Scenes: Henri Christophe: A Chronicle in Seven Scenes (1949) is the first play by Derek Walcott, written when he was 19 years old.  It is about the self-declared King Henri Christophe of Haiti, a former slave who became a general under Toussaint Louverture in the Haitian Revolution.  Later, he ruled the northern part of the nation from 1807 to 1820, first as president and from 1811 as king.  At the time the South was governed by the president Alexandre Pétion, a "gens de couleur" (free man of color; in Haiti, such people were generally of French and African descent).

Cap-Haïtien Arrondissement: Cap-Haïtien (Haitian Creole: "Kap Ayisyen" ) is an arrondissement in the Nord department of Haiti and is the second important city of the country.  Known as the historical and touristic capital of the country.  Cap-Haïtien was founded in 1670 by the French settler Bertrand d'Ogeron de La Bouëre.  As of 2015, the population was 356,908 inhabitants.  The city is governed by three mayors elected by popular vote every 5 years and also represented in the National Assembly of Haiti with one member elected every 4 years.  Postal codes in Cap-Haïtien Arrondissement start with the number 11.

State of Haiti: The State of Haiti (French: État d'Haïti, Haitian: Leta an Ayiti) was the name of the state in northern Haiti.  It was created on October 17, 1806 following the overthrow of the Empire of Haiti following the assassination of Emperor Jacques I.  The northern State of Haiti was ruled by Henri Christophe originally as "Provisional Chief of the Haitian Government" from October 17, 1806 until February 17, 1807 when he became "President of the State of Haiti".  The 1807 constitution for the State of Haiti made the post of president a position for life with the president having the power to appoint his successor.  On March 28, 1811 President Henri was proclaimed King Henry I, thereby dissolving the State of Haiti and creating the Kingdom of Haiti.

Gonaïves: Gonaïves (Haitian Creole: "Gonayiv" ) is a commune in northern Haiti, and the capital of the Artibonite department of Haiti.  It has a population of about 300,000 people (2011 census).  The city of Gonaïves was founded in 1422 by Indians who named it "Gonaibo" (to designate a locality of cacicat of the Jaragua).  It is also known as Haiti's "independence city".  The Bay of Gonaïves is named after the town.

Cap-Haïtien: Cap-Haïtien (Haitian Creole: "Kap Ayisyen" ; English: "Cape Haitian" ) often referred to as Le Cap or Au Cap, is a commune of about 190,000 people on the north coast of Haiti and capital of the department of Nord.  Previously named, "Cap‑Français" (initially "Cap-François"), "Cap‑Henri" and historically nicknamed, "The Paris of the Antilles", displaying its wealth and sophistication through its beautiful architecture and artistic life.  It was an important city during the colonial period, serving as the capital of the French Colony of Saint-Domingue from the city's formal foundation in 1711 until 1770 when the capital was moved to Port-au-Prince.  After the Haitian Revolution, it became the capital of the Kingdom of Northern Haiti under King Henri Christophe until 1820.

Max Gerbier: Max Gerbier (born 1951) is a Haitian painter.  Born in Milot near Cap-Haïtien in northern Haiti, Gerbier typically paints landscapes of the area surrounding his hometown.  His paintings have been exhibited in France and the United States.

Supporting paragraphs: Cap-Haïtien Henri Christophe
Answer: Bambara