Daughter of Rosalie Benoni Colenbrander (1870-1901) and Walter Harding Bovell Addison (1859-1931).
She trained as a nurse in England. After her two brothers Ernest Colenbrander Addison and Alphonse Colenbrander Addison were killed in action in WWI she returned to South Africa on the SS Galway Castle on 10th September 1918. At 07.30 hrs on 12th September 1918 when two days out from Plymouth, the ship was torpedoed by U-82 and broke her back. At the time she was carrying 400 South African walking wounded, 346 passengers and 204 crew members. So severe was the damage that it was thought that she would sink immediately and it was apparent that U-82 was lining up for another attack. In the rush to abandon ship several lifeboats were swamped by the heavy seas and many finished up in the sea. However, the U-boat did not mount a further attack and the Galway Castle continued to wallow for three days. Destroyers were summoned by radio to rescue survivors who were taken back to Plymouth where it was ascertained that 143 persons had perished, among them Cornelia Addison.