What fueled economic growth but also enflamed old rivalries and contributed to two major wars in the twentieth century was Rearmament.
The Atomic bomb was correctly seen as such a jump forward in modern weaponry that it would end the war with the holder of the weapon being the ultimate victory.
This proved to be true as the dominant powers after the War were the two nations that had the weapons (US and Soviet Union).
A, ruinous policies of taxation.
I don’t know if this will help you But here is what I got about the Mexican American War.
The Mexican-American War (1846-1848) marked the first U.S. armed conflict chiefly fought on foreign soil. It pitted a politically divided and militarily unprepared Mexico against the expansionist-minded administration of U.S. President James K. Polk, who believed the United States had a “manifest destiny” to spread across the continent to the Pacific Ocean. A border skirmish along the Rio Grande started off the fighting and was followed by a series of U.S. victories. When the dust cleared, Mexico had lost about one-third of its territory, including nearly all of present-day California, Utah, Nevada, Arizona and New Mexico.
The intention of the Allies was harsh so that Germany can’t get stronger and rise again.
