war = bad peace = goooood!
"why can't we all just get along?"....noted social scholar Rodney King.
"Peace in our time!"... Neville Chamberlin (shortly before Hitler invaded Poland)
To answer the topic question - In my opinion, it's not an "idea" to kill or die for ones country. This implies someone is author or inventor of war. The fact is that humans instinctively defend themselves, their families, their territory, their way of life, in other words, their country in response to aggresion by those humans who want to control and 'own' them. If you talk to the loved ones of those who have died in wars most will say they are proud of that person and they understand the context that death. When wars of political maneuvering that have no clear purpose in self defense (Vietnam) we start to see protests by those who naively conclude that ALL war is unecessary. These people are well suited to become someones slave.