What was one significant indication that the european feudal system was effective?
similar systems developed in china and japan.
european peasants voted to keep the system in place.
invaders did not manage to attack europe.
the system put an end to the roman empire.

the population grew a lot and was making more money

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.