In 1892, for no reason that anyone can tell, everyone shrunk to 1 inch tall. They have no idea why, but nonetheless, the now much smaller human race recovered, after a few wars of extermination against un-shrunken rats and the like. They even fought a war against expansionist Microhungary in the 1920s. They have undergone some nuclear research, but the smallest possible bomb is still very difficult for inch-tall people to build. The current year is 1970.