Why is power and greed sometimes not the main cause of war?

Why is disharmony sometimes not the main cause of War?

few examples for each

Power & greed are sometimes the main cause of war because:

Power: You are strong & want to gain more land, food, things, etc...
Definition: The possession of control or command over others; authority. Ability to do or act; capability of doing or accomplishing something.

Greed: You are greedy and you want everything to yourself.
Definition: An excessive desire to acquire or possess more than what one needs or deserves, especially with respect to material wealth. Excessive or rapacious desire, esp. for wealth or possessions.

I hope that helps!