You've probably heard of the Diderot effect.
Countrymen having provided their families with the basic necessities which is food,shelther and clothing do not settle for the present.
Then they start looking at the neighboring villages that they may acquire to themselves. Without any second thought what so ever to the aftermath of war, they agree to go to war.
The main aim is to increase wealth and landmass.
However they need an army of soldiers because the inhabitants of the country have certain skill they've mastered.
jack of all trade,master of none.A man cannot practice many arts with profitable outcome
However war is a like a parttime hobby that can be mastered easily.
So it's easy to find a farmer who is a soldier or a blacksmith who also serves his country.
A work tool doesn't make a man skilled. Eventually we overthrow the neighboring village. So we need to protect our city , we need guards and very loyal ones. What are the characteristics of a guardian ?
1.loyal
2.sharpsighted
3.strong
4.quickwitted
It's hard to find a good guardian, that is if any should exist. But dogs are ever faithful. To it owners and love ones it is friendly but to outsiders it is suspicious and ready to attack. This is the perfect companion for a guardian.
Lastly, war is an art but a deadly one. Lives are lost on the battlefield, homes are displaced injuries are sustained all because of early unnecessary acquisition.