|Onigafuchi Defense Alliance||Japanese government|
|Commanders and leaders|
The Dam War was a political conflict between the villagers of Hinamizawa and the Japanese government. The conflict started after the Japanese government elected to construct a dam that would submerge Hinamizawa under water. The government offered the villagers compensation for moving away from the area, though the enraged villagers largely refused.
In the years following the Dam War, a legend known as the curse of Oyashiro became common among the villagers of Hinamizawa; every year, on the night of the Watanagashi Festival, enemies of the village are killed or mysteriously disappear. This is initially connected to the Dam War, though the connections become less concrete as the years go on.
As a result of the conflict, the villagers of Hinamizawa developed a longstanding hatred for the Houjou family, the villagers who were most outspoken in their support of the government. Over time this hatred lessened for most villagers, with the notable exception of Oryou Sonozaki.
- In the "perfect world" of Saikoroshi-hen, the Dam War is peacefully resolved in favor of the Japanese government; the village is set to be submerged in 1984.