Julie
There was the German South West Africa campaign with some minor border raids into SA, the 1914/15 Rebellion in South Africa and the German East Africa campaign. It is likely that his unit was the South African Mounted Rifles.
Chris Boonzaaier (GSWA)
http://1914-1918.invisionzone.com/forums/i...hp?showuser=748 and bushfighter (GEA)
http://1914-1918.invisionzone.com/forums/i...?showuser=20901 are the best sources.
Here is the very best Order of Battle for GSWA from Chris's web site
http://www.trenchfighter.com/40117/40726.htmlAll the service records exist and can be easily accessed but some of these records are sparse.
I will try and give you some pointers.
My recommendation would be to use a private researcher instead of the free but slowwwwwwwww official system.
Carl