Occupied at various times by the Khmer, Malays and Vietnamese, Con Son Island also served as an early base for European commercial ventures in the region. The first recorded European arrival was a ship of Portuguese mariners in 1560. The British East India Company maintained a fortified trading post here from 1702 to 1705 – an experiment that ended when the English on the island were massacred in a revolt by the Macassar soldiers they had recruited on the Indonesian island of Sulawesi.
Con Son Island has a strong political and cultural history, and an all-star line-up of Vietnamese revolutionary heroes (many streets are named after them) were incarcerated here. Under the French, Con Son was used as a major prison for opponents of French colonialism, earning a reputation for the routine mistreatment and torture of prisoners. In 1954 the island was taken over by the South Vietnamese government, which continued to utilise its remoteness to hold opponents of the government (including students) in horrifying conditions. During the American War the South Vietnamese were joined here by US forces.