Changes in pressure cause wind to blow.
A hoplite was a Greek spear warrior that typically served as regular infantry that wasn’t elite, nor sub par.
The "policing of the Western Hemisphere" is a phrase that conveys Roosevelt's attitude when it came to international affairs. Roosevelt believed that the United States was justified in exercising this policing for several reasons. He argued that there had been chronic unrest or wrongdoing in the Western Hemisphere for a very long time, and someone had to put an end to it. Moreover, he stated that the United States would intervene in conflucts between European countries and Latin American countries if the European powers had a legitimate claim. He argued that this attitude would work because it came hand in hand with the Monroe Doctrine. While the Monroe Doctrine was meant to put an end to European intervention, the "corollary" (which stated the US intention to police the hemisphere) was used to justify American intervention.
