Captain William Foster sailed the ship Clotilda, a schooner with a copper sheathed hull about 86 feet long by 23 feet wide. The Clotilda was built in 1855. He sailed to Africa for Timothy Meagher a Mobile, Alabama business man and plantation owner. Meagher believed he could import slaves through Mobile Bay despite the 1807 law prohibiting the importation of slaves. It is thought he did this as part of bet with some friends.
Foster and the Clotilda arrived on the African coast on May 15th 1860 where he picked up between 110 and 160 Africans from several tribes. These men and women were kept below deck for the first 13 days of their trip, but after that they were allowed on deck. There seems to have not been any sickness or deaths on the voyage.
By the time the Clotilda arrived along the United States coast on July 8th 1860, authorities had been alerted. Foster timed his arrival in port for after dark anchoring off the Point-of-Pines while he waited. His human cargo was transferred to a riverboat, and Foster set the Clotilda on fire, let her sink.
A good place to start if you would like to read more is Dreams of Africa in Alabama