Hwacheon, South Korea
Before 1900, Hwacheon was extremely sparsely populated, with only a few small villages alongside major rivers, due to its rugged terrain and harsh winters. Hwacheon Dam was completed in 1944 and the electricity it generated proved to be a boon. However, it was also source of conflict during the Korean War due to its strategic value as both a power plant and potential weapon (by intentionally flooding downstream areas). It ended up well inside allied territory with the establishment of the DMZ to the north in 1953.