Between 1066 and 1814, England and France were at war more than half the time. I have this from Joseph Strayer, who taught me history in college. I've never actually checked the count, but I'm willing to take his word for it. From Hasting to Agincourt to Waterloo, the English and the French had seemingly irreconcilable differences for a very long time.
Every once in a while, Professor Strayer would take five minutes at the end of a lecture and give us a little talk on What Does It All Mean. In the case of England and France, what it means is, if they can bury the hatchet, anybody can.
And now they are staunch allies. Not that they don't occasionally get on one another's nerves -- especially on the personal level. A few years ago I was in Paris for a marathon and I was standing in a line at the Metro waiting to buy "une carte de dix billets." Ahead of me were an English couple. The rather large man was asking the caissier some questions. He spoke in English in a loud voice, which became louder as the interaction went on. I had thought that only Americans did this.
The ticket seller did not resort to the traditional dodge of not understanding English. Instead, he listened, and eventually resolved the Englishman's issues. I noticed that, as things went on, he became increasingly impassive, but there was no hint of anger. Not a sign of the impatience that I myself was beginning to feel.
This is what peace looks like. We are not always going to approve of other people's behavior, or even understand them, but we do need to learn to get along. The alternative is a Lazy Susan of death, turning unpredictably -- for years, for centuries.