As a young child I had a book called Runaway Slave, story of Harriet Tubman. It was one of the few books I owned and I read it over and over. It touched me in a profound way. I am not sure how much the book was real and how much was fiction but it was definitely my introduction to the book genre of historical fiction.
Historical fiction is a made up story based on real historical events. The book may take place in an actual historical setting or be based loosely on real people and/or real events. The book's main character is usually a fictional person living in the historical time period or event of the book. The point of view of the main character may even involve experiences with real historical people in fictional situations not recorded in history.
What I like about historical fiction is the story can make a dull even more interesting by bringing human thoughts and actions by way of story line. It is a great way to introduce children to important events. As a child, a great historical fiction book made me want to do further research on the event the book talked about.
When my teenage son was required to read The Book Thief by Markus Zusak, he became interested in what happened during the holocaust and did a bit of research about it on the internet.