The Ten Woodmen of Oz: The Oz Book for 1999 is an Oz novel written by March Laumer in 1987.
Being set in the then-future of 1999, it features the citizens of Oz (joined by a few characters from the parallel universe of Magic Land) trying to use magic to help clean Earth of pollution, but their efforts accidently cause World War III between the United States of America and the Soviet Union.
Plot:
Ten woodmen led by Princess Dorothy are sent to the great outside world in an effort to convince the powers that be to utilize magic instead of technology in order to dispel the horrible miasma of smog and pollution that covers the entire planet. Their efforts seem in vain, and in fact stir up events that lead to World War III, but though the end result was supposed to be a lessening of pollution in the atmosphere of Earth, the new solution proves just as ingenious!
Background[]
The premise is similar to the classic satirical novel The Mouse That Roared (1955) by Leonard Wibberley, where an absurd neo-medievalist kingdom mediates an end to the Soviet-American Cold War. Not to be confused with "The Mouse that Roared" (2019), an episode of the Dorothy and The Wizard of Oz cartoon.
As with many 1980s novels "set in the future," this story was retroactively made into alternate history by the unexpected breakup of the Soviet Union in 1991.