Ancestry have many entries for Rees's in The Boer War. Below is one, - but with no dates or full name, it's a bit like looking in the proverbial haystack(!)
Romilly. 

W J Rees
Casualty Type:    Died
Casualty Date:    4 Nov 1900
Casualty Place:    Germiston
Rank:    Sergeant
Force:    South Africa Field Force
Regiment:    Welsh Regiment
Battalion:    1st Battalion
Number:    7323