As much as anywhere in Europe, the recent history of the western Balkans has been written in blood. From its role in igniting the First World War, via the occupation and resistance of World War II, and to the battles and barbarity that followed the breakup of Yugoslavia, the people of the region have suffered enough.Last Friday, Ivica Dacic and Hashim Thaci decided to do things differently. After six months of direct talks, the prime ministers of Serbia and Kosovo agreed to normalize relations. They set out a range of practical steps that should help their people to banish fear, enhance prosperity and play a full role as members of the European family.The author is the High Representative of the European Union for Foreign Affairs and Security Policy.This work originally appeared in The International Herald Tribune.We must not exaggerate. This is not the end of the road. It is a fork in the road, and last week two brave men chose the route marked peace. That was not the outcome that many people expected six months ago when I brought Mr. Thaci and Mr. Dacic together in my office in Brussels. They had never met.For years my office had brokered technical discussions about day-to-day issues such as what precisely should happen at the border between Serbia and Kosovo.These talks had reached the point where political impetus was needed, and this meant engaging the two prime ministers.On the afternoon of October 19, Mr. Thaci and Mr.Dacic entered my office in the newly opened headquarters of the European External Action Service. Neither was sure how news of the meeting would be received back home. When our photographer took a single picture of the two men together, I held on to it until the two prime ministers were comfortable for it to be released.Their task was to find a way to help tens of thousands of Kosovar Serbs living in the north of Kosovo.Much has been written about the history of the dispute.The question was how to end it.That first meeting lasted just one hour. Its purpose was not to settle differences but to see whether the time was ripe for a sustained dialogue. I thought it was. More importantly, so did they. Nine more meetings followed. They were sometimes long, up to 14 hours, often detailed, and sometimes tense. At various times, I invited deputy prime ministers and others from both sides to join. An agreement would stick only if it was endorsed by broad coalitions in both Serbia and Kosovo.In the end, both sides did find common ground on the level of autonomy the Kosovar Serbs should enjoy.Back in Belgrade and Pristina their agreement was welcomed across the political spectrum. Much remains to be done to implement the agreement on the ground.Nevertheless, I think it is possible to reflect on the four big lessons we have learned from the past six months.• Brave leadership is vital if lasting change is to be achieved. The normal condition of politics is to exploit dividing lines and incite differences. The demand of peacemaking is to seek common ground and design a shared future. Over the past six months I have seen men from both Belgrade and Pristina evolve from politicians into peacemakers. They knew they were taking risks but, to their great credit, they were not deterred.• Today’s Europe – indeed, much of today’s world – is untidy. We have multiple identities that do not always fit easily into simple 19th-century notions of the nation state. One of the great challenges in so many of today’s disputes is to acknowledge the untidiness and help people with different identities to find ways to share the same space in a spirit of mutual respect. Then we have a chance to grasp the real prize: the celebration of our glorious diversity.• The European Union can make a big difference. It is a great experiment in making diversity work for the benefit of us all. Yes, it has its faults. It is currently facing tough economic challenges. But overall it works.That is why the peoples of Eastern Europe wanted to join as soon as they freed themselves from Soviet domination. Now Serbia and Kosovo want to join.Last week’s agreement has started a process that will enable them to do so.• Hard power – economic muscle and sometimes military force – has its place, but soft power has a big role to play. The EU continues to attract new members not just because it supports trade, jobs and investment, but because it stands for values, such as freedom and democracy, that inspire people round the world.Hard power invites calculation; soft power rewards imagination. What Ivica Dacic and Hashim Thaci showed when they came to my office was they had the courage to imagine a better future for their peoples.Here, then, is my hope. (I stress “hope”: it is not yet a certainty). For the past hundred years the western Balkans have been known as a cradle of war. From now on, may it be known as a cradle of peace.