Ive always loved to learn about WWII, so when I picked Anne Franks' Diary of the bookshelf when I was 9 or 10y/o, I instantly fell in love with it.
Anne's perception on her life, the war and many other things is much deeper than anyone would expect from a 13year old.
Annes' emotions come through clearly on the page, so you can tell how she felt by just reading her diary.