What event occurred as a result of the serbian assassination of ferdinand, heir to the throne of austria?

formation of the league of nations
spanish-american war
world war i

World War I

Explanation:

That "incident" caused the first World War... that spread all over Europe.  At the end, even Japan and the United States were part of that conflict.

The war itself claimed over 15 million lives, about half military and half civilian.

But the devastation of the war also prepared the perfect conditions for the spread of the 1918 influenza pandemic... which killed anywhere between 50 and 100 million people.  That is the real human cost of WWI.

At the end, all parties agreed that there should never be another war as extensive as that one... yet.. only 20 years later... WWII.

world war i began in 1914, after the assassination of archduke franz ferdinand, and lasted until 1918. during the conflict, germany, austria-hungary, bulgaria and the ottoman empire (the central powers) fought against great britain, france, russia, italy, romania, japan and the united states (the allied powers). to new military technologies and the horrors of trench warfare, world war i saw unprecedented levels of carnage and destruction. by the time the war was over and the allied powers claimed victory, more than 16 million people—soldiers and civilians alike—were dead.

explanation:

the western roman empire flourished, but the eastern portion of the empire struggled.