It would be hard to think of any academic thinkers whose thought wrought greater destruction than Marx and Nietzsche (note that I leave out religious leaders and politicians). These words of Nietzsche, for example:
In the coming century, there would be a “new party of life” which would take humanity to a higher level, “including the merciless destruction of everything that is degenerate and parasitical.” Life, he said, is “appropriation, injury, conquest of the strange and weak, suppression, severity …”
Quoted by Macmillan, Margaret (2013-10-29). The War That Ended Peace: The Road to 1914 (Kindle Locations 4921-4923). Random House Publishing Group. Kindle Edition.
The young Serbian nationalists who carried out the assassination of Archduke Franz Ferdinand and so precipitated the Great War were deeply impressed by Nietzsche’s views...
...Part of Nietzsche’s appeal was that it was easy to read a great deal into his work, and people including socialists, vegetarians, feminists, conservatives and, later, the Nazis did. Sadly, Nietzsche was not available to explain himself; he went mad in 1889 and died in 1900, the year of the Paris Exposition.
Macmillan, Margaret (2013-10-29). The War That Ended Peace: The Road to 1914 (Kindle Locations 4924-4925). Random House Publishing Group. Kindle Edition.
In setting the scene for World War I looks at international events and tensions, and the frequently incompetent and foolish leaders, but also at the social and economic circumstances and the huge shifts human thought that were taking place. Capitalism was crowding the old aristocracies both from above, by creating a new wealthy class and below, by provoking the formation of workers unions. Darwin, especially as misunderstood by Social Darwinists and philosophers like Nietzsche led to a worldview in which war was a necessary process in the service of natural selection.