The reason why people from many religious groups settled in the middle colonies was because they were able to freely practice their religion in these colonies without fear of being hunted down for their beliefs while in other colonies they could possibly have been persecuted.
The immediate cause of World War I that made the aforementioned items come into play (alliances, imperialism, militarism, nationalism) was the assassination of Archduke Franz Ferdinand of Austria-Hungary. ... This assassination led to Austria-Hungary declaring war on Serbia.
While it was true that the cotton gin reduced the labor of removing seeds, it did not reduce the need for slaves to grow and pick the cotton. In fact, the opposite occurred. Cotton growing became so profitable for the planters that it greatly increased their demand for both land and slave labor.