The war had brutalized European society, which had grown accustomed during the largely peaceful 19th century to think that peace was the normal state of affairs.
Whiskey Tango Foxtrot? Russia was growing in the 1960's and 1970's? The 19th Century was peaceful in Europe? Ever heard of Napoleon? The French Revolution of 1848? The Crimean War? The Franco-Prussian war? The Spanish American War (yes, I know it wasn't fought in Spain, but still . . .).
The article said Russia was growing before WWI, not during the 1970s. Also it said the 19th century was relatively peaceful, not without war.