Should countries leave pieces of their history out, especially that which is negative, when documenting these stories? Explain

I believe that countries should share all information of their history. Even if it is about defeats and bad things that they have done in the past that they might not be proud of, at least the people will know all the things we have faced and overcome in our history. For example, Germany might not tell their people about the Holocaust and all the lives that the Nazi's took. But it is still a huge part of German history and the people should be taught about it even if they were in the wrong during that era. There will always be things that we are not proud of doing and we wouldn't like no one to know about, but its how we learn from our mistakes and move forward.