Militarism is a political idea that focuses on building a military. It is built around the idea that nations need to have strong militaries if they are to protect the interests of their people. If those interests create a conflict with the interests of another nation, the military is there to solve that through things like wars. Militarism is usually about territorial expansion.
It influenced them because the nations needed colonies in order to stay relevant on the worldwide market and be powerful. Britain and France had numerous colonies while Germany wanted to get some of them and Austria-Hungary and Ottomans had problems with people wanting to become independent. This resulted in all of them heavily focusing on their militaries which eventually brought world war 1.
The answer is to prevent a British invasion from the north because it would have been very easy for Britan to destroy them because they were weak in the north.
Generally speaking it would be "political science" that is the academic discipline that focuses on the study of the roles and functions of government, although in some institutions the major is simply "government".
Before the advent of public conventions, the nominees for president were selected by a small group of privileged citizens in closed meetings. These individuals would have been adult white male citizens of a certain level of wealth and power.
