Is War Ethical?

As a philosopher who believes that happiness can be achieved by having a peaceful life, I'm against of war,its consequences and the reasons why people engage in it. Humans should live in peace with themselves and the society. Conflicts between countries and cultures must be resolved in a nonviolent way because with war as the only escape, nothing will be solved and more problems will arise , therefore happiness will vanish from everything and everyone . War means anger , hatred over another person, another nation. It's a decision based on pessimistic and evil actions. I believe that everyone can achieve happiness and maintaining peace drives to happiness among every person.