A Time for Reflection.

[kahnjar1]

Originally Posted by ariel

Perhaps, in retrospect, it was the most consequential war: millions of dead for no good reason except for the German wish to become an European hegemon and the unwillingness of Britain and France to allow it, 4 Empires destroyed, peculiarly fratricidal one ( German, Russian and British rulers were cousins), and the ultimate results was the mutation of Germany into a Nazi state and of Russia into a Stalin's Gulag with the horrifying WWII being an inevitable outcome occuring only less than 20 years after " the war to end all wars"....

We are still living with the consequences of the disastrous decisions of European rulers in August 1914....

Not quite as simple a cause as described by ariel but rather than re state what Wiki says, here is the link https://en.wikipedia.org/wiki/World_War_I As you will read, there were several events which eventually lead to the wider conflict.
Stu