one of the few interesting facts learned from "the long recessional," a busy, but somehow empty biography of rudyard kipling, is this: the term (and method) "concentration camps" came from spanish military efforts to push civilian populations into "campos de reconcentracion" during the struggles of the late 1890s.
a few years later, in 1900, british general Kitchener decided to move Dutch-speaking civilians into camps while fighting the Boer War. this move shocked both left and right in England. Kipling and other conservatives railed against a policy that let Boer fighters act like "apaches . . . having the time of their lives" while knowing their wives and kids were being looked after.
but camp conditions were bad. two radical MPs (unnamed in the book) borrowed the spanish term and called them "concentration camps" meant for "extermination."
this little slice of history ties together Geronimo (subdued only a decade before), the end of Spanish rule in Cuba, and the consolidation of English rule in South Africa. apparently later, Nazi propaganda claimed England had invented the term and practice.
concentration camps are literally meant to concentrate populations: hence, the US concentration of japanese-americans in 1942 deserves this term. while these camps were not extermination camps, they are inarguably concentration camps.