The first successful separation procedure wasn't performed until 1955
Up until the 20th century, most conjoined twins avoided attempting to be separated due to the lack of medical understanding and the high risk of death. In fact, it wasn’t until 1955 that the first successful separation of conjoined twins occurred. Dr. Harold Voris performed the surgery at Mercy Hospital in Chicago.
The first documentation of an attempted separation surgery took place in the Byzantine Empire in the 900s. Then, doctors tried to remove the dead body of conjoined twins, for which they were partially successful: the other twin managed to live a whole three days after the surgery. Over the years, other attempts have been made to try and free conjoined twins, but they were unsuccessful. Other times, the connected siblings were offered the option of a medical procedure, but didn’t want to be separated. Then, in 1955, Dr. Voris and his team successfully separated a pair of conjoined twins who were attached at the head (craniopagus).