Russia mobilized a vast army against Austria-Hungary in favour of Serbia, one of their allies. And then on August 4th 1914 Germany entered WWI when they invaded Belgium, thus starting WWI. In September, 1915 Germany was putting in a lot of effort so America would not enter WWI. But on April 6th, 1917 the USA enters the war after President Wilson outlined his case to congress about WWI, just four days before.
There are so many more events that took place during world War One, these are just a few. Leading up to USA involvement in the war.
Because they invented the Olympics which was a challenge of strength and courage in their social structure. if the male population could not achieve this they were unworthy to marry and produce offspring..
