From Wikipedia
During the Second Boer War, the UK pursued the policy of rounding up and isolating the Boer civilian population into concentration camps.
The wives and children of Boer guerrillas were sent to these camps with
poor hygiene and little food, although this was remedied to some extent
as time went on. The death and suffering of the civilians, according to
many scholars, is what broke the guerrillas' will. The "pacification"
theory has been repeated many times in warfare since.