People go to war for one of two reasons: to protect their way of life or to better their way of life. There are many examples throughout history that showcase both of these reasons.
In the ancient Middle East, the people went to war because they wanted to better their way of life by getting more water, more resources and better farmland. The people that the Middle East people attacked defended themselves because they wanted to protect their way of life.
Another example can be seen during the Persian Wars between Greece and the Persian Empire. The Persian people wanted more land, food and resources. They also believed that the Greek shipping trade in the Aegean Sea and the Mediterranean Sea was creating problems for their Persian shipping trade. The Persians went to war with Greece for both reasons. The Greeks fought back because they wanted to protect their way of life. The Greeks knew that the Persian Empire would destroy their elected government and the other parts of their society that they cherished.
An example with the United States includes the Revolutionary War. The American people wanted to protect a new way of life with their declaration of independence. They fought Great Britain because they wanted to protect the new lifestyle and society that they had created.