War is an organized activity. Unlike the heated argument between individuals that might lead to violence, war requires someone, or some group, to gather, persuade, and organize a larger group of people to engage in violence against another group of people(s). The question then becomes; what is it that inspires or drives the 'someone,' or 'some group' to organize others for war? The answer is status seeking.
Can you imagine that Henry V, King of England, did not have enough people genuflecting and humbling themselves to him? That he did not have sufficient castles and keeps, land and lords to be content? War with France was not for him a matter of insufficient wealth, it solely a matter of pride and status. He took his people to was so he could prove that he personally was superior to the King of France.
This same lust for, and pursuit of status is what drives American CEO's, with already obscene and unspendable wealth, to constantly seek more. The mantra is if so-and-so makes so much, I must make more.
We will have war so long as we maintain as a necessity, the creation of heirarchical structures of organization. Such structures inevitably reward the status-hungry internally, and subsequently demand a similar competitive relationship with other similar organizations. That is why, irrespective of the type or stated purpose of an organization, e.g. religious organizations, political organizations, etc, there will be conflict, and between nations, war.
The solution is to move from our current paradigm of organizing people to achieve common aims, from large to small. Smaller groups tend to work more cooperatively, whereas large groups appear to require specialization, and heirarchy. Eliminate the latter and you go a long way to eliminating war.