Written in 1907, The Iron Heel, by Jack London, caused an outcry on publication. Condemned for alarmism, London was subsequently proved right by events in Europe in the 20s and 30s. Of particular relevance at the moment is chapter "The End", which comes some way before the end of the book- it has a few rough edges, this work, just like old Jack himself ! Dialogue is turgid, but the vision is terrifying.
Another moot point is the fact that Orwell is known to have read the Iron Heel, so did he plagiarise it ?