Robert Hamill Nassau (1835-1921) was born in Newtown Square, Pennsylvania. He went to the Lawrenceville School in Lawrenceville, New Jersey, continuing his education at the College of New Jersey. From 1856 -1859 he moved on to the Princeton Theological Seminary and obtained a medical qualification from Pennsylvania Medical School in1861. Nassau was an ordained minister and a medical doctor. On the instigation of the Presbytery of New Brunswick he joined the Presbyterian Board of Foreign Missions as a missionary, with his first posting being to the African island of Corisco off the coast of present day at Equatorial Guinea. He and his wife Mary Cloyd Latta served there and at Benito on the mainland until her death in 1870.