The following lists events that happened during 1921 in South Africa.

Incumbents Monarch: King George V Governor-General and High Commissioner for Southern Africa: Prince Arthur of ConnaughtArchontology.org: A Guide for Study of Historical Offices: South Africa: Governors-General: 1910-1961 (Accessed on 14 April 2017) Prime Minister: Jan Smuts Chief Justice: James Rose Innes

Events May 3 – The second census of the Union of South Africa takes place. 24 – The Bulhoek Massacre takes place with an estimated 163 killed.

July 30 – The Communist Party of South Africa is established.

December 28 – White gold miners on the Witwatersrand go on strike in the Rand Rebellion.

Unknown date Dagbreek men's residence opens at Stellenbosch University.

Births 30 May – Jamie Uys, actor and film director. (d. 1996) 21 July – Vusamazulu Credo Mutwa, Zulu sangoma and author (d. 2020)

Deaths 10 September – John Tengo Jabavu, editor of South Africa's first newspaper in Xhosa. (b. 1859)

Railways

Railway lines opened

1 November – Transvaal – Pretoria West to Roberts Heights, .Statement Showing, in Chronological Order, the Date of Opening and the Mileage of Each Section of Railway, Statement No. 19, p. 188, ref. no. 200954-13 28 November – Natal – Booth Junction to Cato Ridge, .

Locomotives Two new Cape gauge locomotive types enter service on the South African Railways (SAR): February – A single experimental 2-6-0+0-6-2 Garratt articulated steam locomotive, the first Cape gauge Garratt in South Africa. June – The first of seven Class GB 2-6-2+2-6-2 Garratt locomotives.

References