Serbia lost 16% of the its population in the ensuing war. That’s a staggering price to pay, especially in view of the fact that Serbia today is smaller than it was at the time of WWI. These men (including their trainers) should have been shot and buried in unmarked graves before they embarked on their mission.
They did NOT however, anticipate the scope of their folly.
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Serbia is larger now than it was in 1912. It is a little smaller than it was in 1914 (after the Balkan Wars, when it gained a lot of territory). Vojvodina now belongs to Serbia—before WWI it was part of Austria-Hungary.