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.

the alfred thayer mahan award for literary achievement is awarded each year by the navy league of the united states. the award is named for an american naval historian and theorist, rear admiral alfred thayer mahan, united states navy who, through his writing, provided stimulus and guidance to those who share in the defense of the nation. presented since 1957, "this award for literary achievement is awarded to a u.s. navy officer, u.s. marine corps officer, enlisted service member, or civilian who has made a notable literary contribution that has advanced the knowledge of the importance of sea power in the united states."[1]

the answer is a. hope this