What historical circumstances led to the Feudalist Hierarchy in Europe.( Also Japan if u know the answer)

Fall of the Western Roman Empire.

Explanation:

After the fall of Western Roman Empire Germanic tribes settled and created many states on its soil. As it was hard to established certain political authority, rulers of these kingdoms introduced feudal system, that was based on loyalty. It was the dominant form throughout Middle Ages. In France for example lasted until the Revolution of 1789.

answer: what was the us involvement in ww1? although the u.s. tried to remain neutral when ww1 broke out, it finally joined on april 6, 1917 after declaring war on germany. the reason for america to become involved in ww1 was germany's unrestricted submarine warfare, which had already sunk several american merchant ships.

explanation:

i think it’s will be a yes