What circumstances led Bismarck to make such a statement? What evidence did he have backing this statement? How much did he foresee with this prediction, if anything at all?
There's a pretty thorough rundown with more recent answers from /u/ragingrage and /u/aleksx000 here.
If you copy and paste your quote into a search of this sub you'll get your answer:
https://www.reddit.com/r/AskHistorians/comments/235yuy/how_likely_is_it_that_the_quote_by_otto_von/