Answer:
In the First Barbary War, which was started by the United States refusal to pay immunity fees to the North African Barber states, it saw the succesful use of the United States Marines. After the marines stormed the city of Derna, thus giving the US leverage over the Tripolian government, thus seeing the release of all American sailors, and goods, along with the end of the First Barbary War.
The blending of greek and roman philosophies with christian ideas
I think it would be the failure to pass treaties. European nations are often in conflict over land territories and vast riches of the country. Another reason why the European countries always care in conflict, it would be religion. Many of them are firm believers Christianity. I think this was the reason why there was Crusades occur.
