How did the United States respond to the
terrorist attacks of September 11, 2001?

After the September 11, 2001 attacks, the U.S. government responded with immediate action (including rescue operations at the site of the World Trade Center and grounding civilian aircraft), and long-term action, including investigations, legislative changes, military action and restoration projects

Explanation:

1. it was caused by feudalism

2. charlemagne used christianity as a major cornerstone for his rule. cloisters were built all over the empire to act as centers for the (re)population of the vast european wilderness.

3. the europeans feared the next raid every time chetak

i'm not so sure about #6. but i hope i you with the first 3.