His main field is the history of the Second Anglo-Boer War (1899–1902), to which he contributed many scholarly books and articles, both as an author and editor.
[1][2] His 1999 book, Life on Commando during the Anglo-Boer War 1899-1902, was runner-up for the Sunday Times Alan Paton Award.
He received the Stals Prize from the Suid-Afrikaanse Akademie vir Wetenskap en Kuns (South African Academy for Arts and Science) in 1998, and is a former editor of 'Historia', the journal of the South African Historical Association.
[5][6] In 1998 Pretorius received the Stals Prize for Cultural History from the Suid-Afrikaanse Akademie vir Wetenskap en Kuns (SAAWK, South African Academy of Science and Art) and in 2001 the Prestige Prize from the Federasie van Afrikaanse Kultuurvereniginge (FAK, Federation of Afrikaans Cultural Associations).
In 2019, he was awarded the annual Jan H. Marais Prize for Outstanding Contribution to Afrikaans as an academic language.