During the lead-up to the war and her time in hiding, Anne Frank certainly heard a lot about the death and destruction that is caused by war. She reflects on this senselessness throughout the writing of her diary. She contemplates how the war causes everyone to suffer, not just the Jews.
All we can do is wait, as calmly as possible, for it to end. Jews and Christians alike are waiting, the whole world is waiting, and many are waiting for death.
We can see in her writing that Anne is very concerned that so many people are suffering because of the war. She blames politicians for wasting the lives of so many people. However, she also recognizes that this senseless bloodshed has something to do with human nature as well. It is the common person who actually takes part in waging war and inflicting harm on others. There is an innate urge to destroy and kill that exists in the soul of mankind. She feels that unless humanity as a whole can change, unless it can go through some sort of complete metamorphosis, war will continue to be part of the human condition.
This is not to say that Anne is a complete pessimist. She also writes about her faith in the goodness of people. She knows that other people are putting themselves at risk to help her and her family. However, it is difficult for Anne not to also contemplate the brutality of mankind, considering all that she is going through.