How did the lives of knights and nobles demonstrate the importance of warfare in the middle ages

The duties of knights and nobles clearly show the importance of warfare in the Middle Ages due to the fact that there main objective is to serve in the battle.  The knight was expected to be trained for a war and display courage during the battle and serves their loyalty to their lords while nobles are tied to farming which provides food to the empire.

uncle sam would be tossing and turning in his grave : *)

it foreshadows the theme of the paragraph and hints the topic that will be discussed in the paragraph!