Unfortunately, there is no such thing as world peace (at least not today) and there are countries that have wars because they disagree on topics, just generally dislike each other, or because they are run by loons. You need an army, organization, or protector of some sort to assure your nation and people are safe if things get out of hand.
Because He died just to defend our Country
To defend your country.
To defend our country.
If you don't defend your nation, someone will take it from you .
Nationalism - having pride in your country, willing to defend it
We tried to defend his country.
To defend country it is serving.
To defend the country from attack
The country can defend itself should another country attack it.
It is called a Pre-Emptive attack if I am not mistaken
Chinese workers developed the Great Wall to defend their country and made it long to defend along the side of the country to not get ambushed by frightening enemies.
A war where you defend your own country.