Short answers, pulled from the story.
Jean-Jacques Dessalines was the first Emperor of Haiti and the leader who declared Haitian independence on the 1st of January 1804. He is considered one of the fathers of the nation alongside Toussaint Louverture, and under his rule Haiti became the first country in the Americas to permanently abolish slavery.
The Battle of Crête-à-Pierrot took place on the 11th of March 1802, when Dessalines and 1,300 men defended a small fort against 18,000 French attackers. Dessalines held a lit torch near an open powder keg to inspire his troops, threatening to blow up the fort if the French broke through. After a 20-day siege, his forces escaped through enemy lines into the Cahos Mountains.
Between February and April 1804, Dessalines ordered the killing of the remaining French colonists in Haiti, resulting in between 3,000 and 5,000 deaths. Some historians cite the threat of a French reinvasion and the reimposition of slavery as reasons for the order. Dessalines exempted Polish Legionnaires who had defected from the French side and Germans who had not participated in the slave trade, granting them citizenship.
Dessalines was proclaimed Emperor by the generals of the Haitian Revolutionary army on the 22nd of September 1804 and was crowned Emperor Jacques I on the 6th of October 1804 in the city of Le Cap. The imperial constitution of the 20th of May 1805 named him emperor for life with the right to name his successor.
Dessalines was assassinated on the 17th of October 1806 at Larnage, now known as Pont-Rouge, north of Port-au-Prince, while traveling to suppress a southern insurrection. Alexandre Pétion and Étienne-Élie Gérin were among the conspirators within his administration. His body was dismembered by a mob; it was later gathered by a vivandière named Dédée Bazile and buried at Church Ste-Anne.
The national anthem of Haiti is called "La Dessalinienne" and is named in honor of Jean-Jacques Dessalines. It was written in 1903, nearly a century after his death, as part of a reassessment of Dessalines as an icon of Haitian nationalism.