I feel that this is quite a common misconception. Many people have a lower opinion of ourselves because of how we've fought wars in the past, and refer to humankind in general as "naturally evil," or that war/fighting is "in our blood" and will always be a constant of our civilization. However, I feel like we are on the road to world peace. As nations continue to modernize, people are increasingly realizing the value of human life.
Back in World War II, America dropped atomic bombs on Hiroshima and Nagasaki because those cities had a high civilian population, and they killed tens of thousands of Japanese citizens. Now, we would never,
ever do anything like that again- we refuse to take the lives of any civilians of any nation despite the potential military advantage. On June 6, Americans and other allied countries stormed the beaches of Germany, knowing that we would lose thousands of men in the process. Now, it's a huge deal when ten American soldiers are killed in combat, and we try to only conduct operations when we have a high confidence that every man will make it out alive. Orginizations like NATO are formed to prevent wars. Modern, developed, civilized countries like America and most European nations do everything they can to avoid violent conflicts, with war only being a last resort after all other diplomatic options are exhausted.
America is currently engaged in counter-terrorist operations in the Middle East and Central Asia, but we are not actually at war with any other nation. I'm starting to think that a war between two developed nations would be seen as immoral and could not happen, and all other actions would be taken to resolve conflicts and reach a solution or a compromise. As nations continue to modernize and reach this civilized mindset, the wars and conflicts around the world will diminish and disappear.
I am confident that you and I will both live to see the day when there are no wars, and the idea of killing, internationally or otherwise, is seen as an international wrong. Europe is pretty much already in a state of widespread peace, as they're not actively in combat anywhere, and America is close.
...time and time again that in times of peace we always bring ourselves to violence...
History has indeed shown this to be true, but it's also true that in times of violence, we always bring ourselves to peace. Wars and violence, even in ancient times, were not as prevalent as you may think- Plenty of citizens of ancient cultures went their entire lives without seeing any conflict. Wars were spread out, separated by long time periods of peace.