The year Charles Robert swart became president?

Charles Robert Swart was the last Governor-General of the Union of South Africa and became the first President of the Republic of South Africa from the date of its creation.

Source: pages 157-165 Suid-Afrikaanse Geskediedenis in Beeld by Antony Preston - Bison Books Ltd, Kimbolton House 117A Fulham Rd, London SW3 6RL under the original title "Pictorial History of Southern Africa" 1989