Daniel Beach Bradley (1804-1873) was born and raised in Marcellus, New York. He first applied to the American Board of Commissioners for Foreign Missions in 1832 for appointment as a missionary. Bradley became a physician in 1833 after studying medicine at the University of New York. In 1834 he married Emelie Royce (1811-1845) of Clinton, New York. That same year, the Bradleys were sent to Siam by the A.B.C.F.M. In 1845 Emelie died of tuberculosis. Dr. Bradley subsequently returned to the United States, where he married his second wife, Sarah Blachly Bradley (1817-1893) in 1848. In that year he parted with the A.B.C.F.M. over doctrinal differences and was commissioned by the American Missionary Association to continue work in Siam. In 1850 he returned to Siam and nine years later became a financially independent missionary.

At the Siam Mission, Dr. Bradley practiced medicine out of a floating house used as a dispensary. He was especially known for his mass inoculation during a small pox epidemic and ties to Siam royalty through his medical pursuits. Furthermore, Bradley published numerous tracts and newsletters in an effort to both educate and proselytize the Siamese people. His most notable literary accomplishment was the publication of the Dictionary of the Siamese Language, completed in 1873, also the year of his death.

In his lifetime, Dr. Bradley had at least seven children: Sophia Royce, Emily Jane, Cornelius Beach, Irene Bell, Sarah Adorna, and two who died in infancy. Cornelius Beach Bradley (1843-1936) became pastor of the Siam Mission Church after his father's death. He was affiliated with the American Missionary Association as a missionary in Siam from 1871-1874. He later returned to the United States where he worked as a college professor.