* Yellow fever: This mosquito-borne disease was a major killer of European soldiers in the tropics, and it claimed the lives of thousands of French troops in Haiti.
* Other diseases: In addition to yellow fever, the French army was also plagued by other diseases, such as dysentery, malaria, and typhoid.
* Starvation: The French army was often unable to obtain sufficient supplies of food, and many soldiers died of starvation.
* Guerrilla warfare: The Haitian rebels waged a highly effective campaign of guerrilla warfare against the French, which made it difficult for the French to control the island.
* Lack of support from France: The French government was unable to provide adequate support for the army in Haiti, and this made it difficult for the French to sustain their campaign.
As a result of these factors, the French army in Haiti was eventually defeated, and the Haitian people gained their independence.