The more that a country had, the more powerful it became. this is the basis of mercantilsm

The answer is precious metals.

Mercantilism was an economic system dominant in modernized nations throughout the Renaissance period. It stressed that the wealth and economic power of a nation-state were based on the possession of large amounts of gold and silver. Therefore, many European powers of that time took an imperialist expansion policy in order to search for these metals and also maintained economic policies towards monopoly and protectionism to keep the control on the resources and avoiding them from fleeing to other markets.

on april 6, 1917, the u.s. joined its allies--britain, france, and russia--to fight in world war i. under the command of major general john j. pershing, more than 2 million u.s. soldiers fought on battlefields in france.