All I really know about Karl Marx is that he didn't like capitalism. So I would have to say the invention of capitalism.
The League of Nations was originally formed to promote world peace but was a <span>failure and one of the causes of WW2.</span>
The southern colonies' economy had growing labor demands
This is because the South's economy relied on the agriculture, which required more physical labor than the industrial factories the North relied on.
IRON WAS CHEAPIER SO CITIZENS COULD AFFORD IT!