The slave ship União left the African coast carrying enslaved Africans toward Brazil. About 683 people had been taken aboard.

Vessel: União; flag: Portugal / Brazil; rig: Brig; estimated standardized tonnage: 244. People recorded in connection with the voyage: Captain: Silva, Henrique José Vieira da. The voyage began at Pernambuco, place unspecified on 1840. Principal recorded place where captives were acquired: Luanda (West Central Africa and St Helena). Principal recorded disembarkation place: Catuamo and Maria Farinha. Recorded duration of the captives' Atlantic crossing: 43 days. Estimated mortality during the crossing: 27.0%. Recorded outcome: Voyage completed as intended.