The period between the end of the middle ages and the present
(apex)
The name for this idea is "Domino Effect" - this is a theory that says that if one country falls to Communism the neighboring countries would also fall to Communism, much like pieces of Dominos fall when a neighboring piece fell.
This theory was important in the Foreign politics of the US during the cold war.
The key victory of the Mexican war is when Winfield Scott went through Mexico and captured Mexico city.
