16 – The SS Mendi, a troopship, sets sail from Cape Town to Le Havre, France, transporting 823 members of the 802nd South African Native Labour Corps.
21 – The SS Mendi is struck on the starboard side by the SS Darro, an 11,000 ton liner, and sinks with 646 people losing their lives.
The Industrial Workers of Africa (IWA), the first predominantly black trade union in South Africa, is established in Johannesburg.
The Castle in Cape Town is handed over to the South African Defence Force.
Gold mining company Anglo American Corporation is founded by Ernest Oppenheimer.
27 October – Oliver Reginald Tambo is born in Bizana.
20 December – Petrus Hendrik Hugo, World War II fighter pilot.
18 January – Andrew Murray, author, educationist and pastor, dies at the age of 88.
5 March – Natal – Izingolweni to Harding (Narrow gauge), 39 miles 56 chains (63.9 kilometres).
20 June – Natal – Gingindlovu to Eshowe, 20 miles 2 chains (32.2 kilometres).
Three new Cape gauge locomotive types enter service on the South African Railways (SAR):
November – Ten Class 16B 4-6-2 Pacific type passenger steam locomotives.
Seven Class K 4-6-4 tank locomotives that had been built for the Philippines but could not be delivered.
At least four 2-8-2 Mikado type steam locomotives, built for the Chemins de Fer du Bas Congo à Katanga and obtained on temporary lease to alleviate the critical wartime shortage of locomotives.
1917 in South Africa Wikipedia